^ 


"CHICAGO  MEDICAL  BOOK 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


PLATE    I 


White  Cells  of  the  Blood,  Leukocytes,  acting  as 
Phagocytes  or  Devouring  Cells;  Streptococci  in 
Chains  being  Consumed. 


ELEMENTARY 


BACTERIOLOGY 


PROTOZOOLOGY 

IK 

FOR  THE  USE  DB!  NE^ES 

(r 


ERBEttT,  FOX,  M.D. 


DIRECTOR   OFi  THEVj\fl|LLIAM    BETTER    LABORATORY    OF   CLINICAL   MEDICINE   IN 

THE  laNIVEftSlTY*  pf  PENNSYLVANIA ;    PATHOLOGIST   TO    THE 

,  ZOOLOGICAL    SOCIETY    OF    PHILADELPHIA,    ETC. 

MAJOR,    M.  C.,  'U.S.A. 


THWD  EDITION,  THOROUGHLY  REVISED 


ILLUSTRATED  WITH  68  ENGRAVINGS  AND 
SIX  COLORED  PLATES 


LEA  &  FEBIGER 

PHILADELPHIA  AND  NEW  YORK 


COPYRIGHT 

LEA   &   FEBIGER 

1919 


TO 
MY  WIFE 


M347986 


'   x 

I 


Vtf 


PREFACE  TO  THE  THIRD  EDITION. 


THE  revision  of  this  book  herewith  presented  is  due  to  the 
need  for  certain  changes  and  additions  to  bring  it  up  to  the 
state  of  information  of  the  present  year.  It  has  no  special 
military  significance  because  the  principles  involved  in  the 
subject  have  changed  little  or  none  by  developments  in  mili- 
tary medicine.  It  was,  however,  inevitable  that  some  new 
matter  with  direct  military  applicability  would  have  to  be 
introduced,  but  this  is  in  the  line  of  adaptation  and  not  of 
change  in  principles. 

Attempts  have  been  made  to  increase  the  value  of  the 
book  to  the  nurse  at  the  bedside  by  adding  more  details  of 
practice,  at  the  same  time  elucidating  the  principles  upon 
which  the  practice  is  based  so  that  it  may  be  valuable  to  the 
teacher.  It  is  hoped  that  the  information  is  presented  in 
such  a  manner  that  laymen  may  be  interested  and  acquire 
some  knowledge  of  transmissible  disease. 

The  author  wishes  to  express  his  appreciation  of  the 
kindly  interest  and  assistance  given  him  by  the  publishers, 
Messrs.  Lea  &  Febiger,  during  the  history  of  this  book. 

H.  F. 

CAMP  ZACHARY  TAYLOR, 
1918. 


(v) 


PREFACE  TO  THE  FIRST  EDITION. 


THE  present  work  has  been  prepared  to  give  the  nurse 
and  the  beginner  an  idea  as  to  the  nature  of  microorganisms 
and  their  relation  to  the  world's  economy,  especially  in 
disease.  For  this  reason  much  technical  material  has  been 
omitted,  especially  in  the  subject  of  biological  differentiation. 
Emphasis  has  been  laid  upon  how  bacteria  pass  from  indi- 
vidual to  individual,  how  they  enter  the  body  and  act  when 
once  within,  and  their  manner  of  exit.  Such  general  informa- 
tion concerning  the  character  of  the  disease  process  has  been 
included  as  seemed  necessary  to  clarify  the  nature  of  the 
microbe  action.  Indeed,  the  subject  matter  in  many  places 
is  but  elementary  bacteriological  pathology.  During  the 
preparation  of  the  work  the  author  has  had  in  mind  a  question 
he  has  been  asked  repeatedly:  How  do  bacteria  produce 
disease?  That  this  question  is  answered  as  simply  and  as 
well  as  our  knowledge  of  today  permits  is  the  author's 
sincerest  hope. 

H.F. 


(vii) 


CONTENTS. 


CHAPTER  I. 

INTRODUCTION — HISTORY — THE  PLACE  OF  MICROORGANISMS  IN 

NATURE      .     ,     ....     .     ........      17 

CHAPTER  II. 

GENERAL     MORPHOLOGY  —  REPRODUCTION  —  CHEMICAL     AND 

PHYSICAL  PROPERTIES     .     ..     -.  •    ' 22 

CHAPTER  III. 

GENERAL     BIOLOGY,     INCLUDING    THE    CHEMICAL     CHANGES 

WROUGHT  BY  BACTERIA  .     .     ....     .     .     ...      32 

CHAPTER  IV. 

METHODS  OF  STUDYING  MICROORGANISMS — STERILIZATION  BY 

HEAT     .     .     .     .     .     .     .     .     ...     .     .     .     .     .      37 

CHAPTER  V. 

DESTRUCTION  OF  BACTERIA  BY  CHEMICALS  AND  THEIR  PRAC- 
TICAL USE        ..V    .    ..".;.  ..."     .     < 49 

CHAPTER  VI. 
THE  RELATION  OF  BACTERIA  TO  DISEASE — IMMUNITY      ...       59 

CHAPTER  VII. 

PREPARATIONS  FOR  AND  PROCURING  OF  SPECIMENS  FOR  BAC- 
TERIOLOGICAL EXAMINATION      .........      73 

(ix) 


x  CONTENTS 

CHAPTER  VIII. 

THE  ACUTE  CHIEFLY  LOCALIZED  INFECTIONS  OF  Pus  NATURE — 

THE  PATHOGENIC  Cocci 79 

CHAPTER  IX. 
THE  ACUTE  SELF-LIMITED  INFECTIONS 98 

CHAPTER  X. 
THE  MORE  CHRONIC  INFECTIOUS  DISEASES  ......     134 

CHAPTER  XI. 

VARIOUS    PATHOGENIC    BACTERIA    NOT    ASSOCIATED  WITH    A 

SPECIFIC  CLINICAL  DISEASE 157 

CHAPTER  XII. 
YEASTS  AND  MOULDS 171 

CHAPTER  XIII. 
BACTERIA  IN  AIR,  SOIL,  WATER  AND  MILK       ......     178 

CHAPTER  XIV. 
DISEASES  DUE  TO  PROTOZOA 188 

CHAPTER  XV. 
DISEASES  OF  UNKNOWN  ETIOLOGY 199 

GLOSSARY  206 


BACTERIOLOGY  AND  PROTOZOOLOGY. 


CHAPTER  I. 

INTRODUCTION— HISTORY— THE    PLACE    OF 
MICRCORGANISMS  IN  NATURE. 

INTRODUCTION. 

THE  study  of  disease  has  brought  to  light  many  facts 
which  demonstrate  the  effect  of  the  association  of  different 
forms  of  life.  Chief  among  these  is  the  fact  that  minute 
beings  live  upon  greater  ones,  either  harmlessly  or  to  the 
detriment  of  the  latter,  The  study  of  these  small  creatures 
is  called  microbiology,  this  being  the  portion  of  general 
biology  in  which  the  use  of  magnification  is  necessary. 
Bacteria  are  classified  as  plants  and  their  study  is  called 
bacteriology.  The  smallest  animals,  protozoa,  are  considered 
in  the  subject  of  protozoology.  To  explain  the  causation  of 
infectious  diseases  the  physician  has  been  obliged  to  study 
both  of  these  subjects,  that  is,  the  large  field  of  microbiology. 
The  lowest  forms  of  life  are  unicellular  bodies  capable  of 
leading  an  independent  existence,  in  contrast  to  the  single 
units  of  the  cell  groups  which  go  to  make  up  the  compound 
organism,  a  higher  animal  or  a  plant.  Some  of  these  single- 
celled  bodies  have  characteristics  placing  them  without 
question  among  the  plants,  while  others  with  equal  definite- 
ness  belong  to  the  animals.  The  line  between  is  by  no  means 
sharp,  and  much  difference  of  opinion  exists  among  investi- 
gators as  to  the  borderline  forms. 

2  (17) 


18  BACTERIOLOGY  AND  PROTOZOOLOGY 

HISTORY. 

The  existence  of  more  or  less  independent  forms  of  life 
invisible  to  the  naked  eye  was  first  proven  about  two  and 
one-half  centuries  ago  by  Van  Leeuwenhoek  and  Kircher, 
who  actually  saw  and  described  what  were  called  animalcule, 
living,  moving,  and  multiplying  bodies  in  the  tartar  from 
teeth  and  in  animal  fecal  matter.  The  first  conception  of 
the  existence  of  such  microscopic  forms  cannot  be  accredited 
to  these  observers,  since  so  long  ago  as  in  the  fourth  century 
B.C.  Aristotle  suggested  the  possibility. 

As  might  be  expected,  these  single-celled  bodies  were 
not  seen  until  the  development  of  lens-making  permitted 
accurate  enlargement.  The  greatest  advances  have  been 
made,  furthermore,  since  the  perfection  of  the  compound 
microscope  in  the  early  years  of  the  nineteenth  century.  It 
is  also  noteworthy  that  those  who  might  be  considered  the 
founders  of  this  science,  so  important  to  physicians,  were 
botanists  and  chemists.  The  most  important  consideration 
for  the  early  observers  was  the  relation  that  these  minute 
bodies  bore  to  the  spoiling  of  food  and  water,  most  physicians 
of  the  past  having  discredited  the  relation  of  bacteria  to 
disease.  The  scientific  world  now  grants  that  communicable 
diseases  are  due  to  some  forms  of  living  virus.  The  first 
opinion  upon  the  relation  of  specific  disease-producing 
bacteria  came  in  the  middle  of  the  eighteenth  century,  bu*; 
such  a  theory  could  not  be  proven  until  about  thirty  years 
ago,  when  Koch  made  it  possible  to  separate  the  various 
individual  bacterial  species  and  enabled  us,  by  a  series  of 
postulates,  to  study  the  relation  of  the  germs  to  their  par- 
ticular disease.  The  great  proof  of  the  existence  of  bacteria 
came  from  the  man  who  may  be  considered  the  founder  of 
the  modern  science  of  bacteriology,  Louis  Pasteur,  a  French 
chemist,  who  demonstrated  beyond  question  that  bacteria 
produce  fermentation,  and  that  fermentable  materials,  if 
protected  from  the  air,  remain  without  bacteria.  There 


PLACE  OF  MICROORGANISMS  IN  NATURE  19 

succeeded  to  this  proof  others  to  the  effect  that  bacteria 
are  ubiquitous,  and  that  they  are  carried  in  dust  or  probably 
alone  by  air  currents.  His  experiments  also  showed  that 
spontaneous  generation  (the  arising  of  living  forms  anew 
from  the  elements  of  nature,  and  not  from  preexisting  living 
forms)  does  not  occur.  The  results  of  Pasteur's  work  received 
practical  application  also  at  the  hands  of  Koch  and  Lister. 
The  former  devised  methods  for  the  cultivation  and  study 
of  the  individual  species  and  followed  this  up  by  discovering 
the  organisms  causing  tuberculosis,  anthrax,  and  cholera. 
Lister,  shocked  by  the  appalling  mortality  in  the  hospitals 
from  gangrene  and  septic  poisoning,  established  methods 
by  which  bacteria  from  the  air  and  from  infected  cases  were 
excluded  from  healthy  surgical  cases.  The  basic  principles 
of  modern  antiseptic  and  aseptic  surgery  are  due  to  him. 

Throughout  all  the  history  of  microbiological  develop- 
ment it  has  been  possible  to  progress  more  rapidly  and 
definitely  with  bacteria  than  with  protozoa.  Bacterial  life 
and  activity  can  be  controlled  very  largely  now,  but  as  yet 
little  or  nothing  is  known  of  the  important  vital  activities 
of  the  minute  animals. 

As  in  the  case  of  bacteria,  so  the  earliest  records  of  pro- 
tozoa are  those  of  Van  Leeuwenhoek's  animalculse.  Their 
natural  history  has  been  gradually  developed  by  Jablot, 
Dujardin,  Prowaczek,  and  Biitschli,  and  the  present  leaders 
in  the  field,  Calkins  and  Doflein.  However,  it  is  only  within 
the  last  score  of  years  that  we  have  been  familiar  enough 
with  these  lowest  animal  forms  to  be  sure  of  their  species 
identity,  and  we  are  yet  imperfectly  informed  as  to  their 
vital  phenomena. 

PLACE  OF  MICROORGANISMS  IN  NATURE.      ' 

The  studies  of  the  life  history  of  bacteria  and  protozoa 
have  been  the  work  of  botanists,  chemists,  and  physicians. 
Through  this  combined  effort  it  has  become  known  that 


20       BACTERIOLOGY  AND  PROTOZOOLOGY 

these  minute  forms  are  present  in  or  upon  or  have  something 
to  do  with  the  life  of  all  the  higher  animals  and  plants.  The 
number  of  species  in  all  is  legion.  The  number  of  species 
pathogenic  for  animals  is  but  small.  A  microorganism  is 
pathogenic  when  it  is  capable  of  producing  some  form  of 
disease  in  the  animal  in  which  it  is  a  parasite.  In  Chapter 
III  some  of  the  known  relations  of  non-pathogenic  bacteria 
will  be  discussed.  It  is  sufficient  here  to  emphasize  the  differ- 
ence between  the  so-called  parasites  and  saprophytes. 
Parasites  are  organisms  capable  of  living  and  multiplying 
within  the  living  animal  body,  sometimes  to  its  detriment, 
while  saprophytes  live  on  dead  matter  and  may  be  found  in 
nature  everywhere — in  air,  soil,  water.  The  body  upon  which 
a  parasite  lives  is  called  the  host.  There  are  a  few  of  the 
parasites  that  can  carry  on  a  saprophytic  existence  for  a 
short  time  (facultative  parasites),  while  others  (obligate 
parasites),  such  as  the  organism  of  influenza,  demand  animal 
juices  for  their  nutriment.  Among  the  protozoa  this  obligate 
parasitism  exists  quite  extensively,  and  many  forms  cannot 
live  at  all  if  their  normal  cycle  of  life  within  the  animal  body 
be  disturbed.  Indeed,  we  know  the  existence  of  many  species 
only  because  they  pass  through  a  certain  development  in 
insects,  then  in  higher  animals  and  back  again  in  insects; 
that  is,  we  only  recognize  them  when  they  produce  disease 
(see  Malaria).  The  saprophytes  include  the  vast  number 
of  organisms  having  important  functions  among  the  higher 
vegetables  and  the  growth  of  these  in  soil.  It  has  been 
suggested  that  at  one  time,  now  long  past,  all  bacteria  may 
have  been  saprophytic. 

The  general  remarks  concerning  parasites  apply  alike  to 
protozoa  and  bacteria,  but  in  medicine  there  is  at  the  present 
time  more  interest  in  the  bacteria.  For  this  reason  only  a 
few  diseases  caused  by  protozoa  are  important. 

In  order  that  the  positions  these  unicellular  forms  occupy 
in  the  living  world  may  be  known  and  used  for  reference  to 
large  works  their  biological  classification  is  given  here.  The 


PLACE  OF  MICROORGANISMS  IN  NATURE          21 

lowest  of  the  orders  among  the  plants  is  called  Thallophyta. 
This  is  divided  into  Algae,  Lichens,  and  Fungi.  The  Fungi 
are  divided  into  Hyphomycetes  (moulds),  Blastomycetes 
(yeasts),  and  Schizomycetes  (bacteriacese  or  bacteria). 
This  family  is  divided  into  Cocci,  Bacilli,  and  Spirilla. 

Protozoa,  the  lowest  animal  class,  present  the  orders 
Sarcodina,  Mastigophora,  and  Sporozoa,  which  contain 
nearly  all  the  forms  of  interest  in  this  work. 


CHAPTER  II. 

GENERAL  MORPHOLOGY— REPRODUCTION- 
CHEMICAL  AND  PHYSICAL  PROPERTIES. 

GENERAL  MORPHOLOGY. 

Bacteria  (sing.,  Bacterium). — In  introducing  the  subject 
of  morphology  a  few  words  as  to  the  technic  of  observing 
bacteria  will  not  be  amiss.  The  compound  microscope  is 
necessary  to  all  microbiological  work.  Since  this  book  is 
devoted  to  principles,  a  detailed  description  of  the  instru- 
ment and  its  operations  would  be  foreign.  Let  it  suffice  to 
say  that  the  compound  microscope  is  a  series  of  finely  ground 
lenses  by  which  exact  pictures  in  definite  magnification  can 
be  obtained.  An  object  to  be  examined  is  placed  upon  a 
glass  slide  and  covered  with  another  but  much  thinner  glass 
cover.  This  is  laid  upon  the  table  of  the  instrument  and  the 
tube  holding  the  lens  placed  at  a  proper  distance  to  obtain 
the  best  light  and  clearest  picture  when  viewed  through  the 
eye-piece  end.  For  nearly  all  microbiological  observations 
it  is  necessary  to  use  a  special  lens  of  high  magnifying  power, 
called  an  oil-immersion  lens,  and  to  introduce  between  the 
lens  and  the  object  glass  a  drop  of  pure  cedar  oil  into  which 
the  lens  front  dips;  this  concentrates  and  filters  the  light. 
The  microscope  is  also  used  to  examine  the  colonies  of 
bacteria.  Bacteria  are  studied  either  in  the  fresh  living 
condition  or  when  stained  by  appropriate  dyes,  especially 
those  derived  from  coal  tar,  methylene  blue,  and  fuchsin. 

Bacteria  are  exceedingly  small  single  cells,  in  their  natural 
state  transparent,  colorless,  and  apparently  homogeneous, 
possessing  a  very  low  power  of  refracting  light.  They  consist 
(22) 


GENERAL  MORPHOLOGY 


23 


of  nucleus,  cytoplasm,  and  a  wall  which  is  probably  a  simple 
superficial  condensation  of  the  protoplasm.     The  ordinary 


'—  6 


FIG.  1. — Microscope:  A,  ocular  or  eye-piece;  B,  objective;  C,  stage;  D, 
"iris"  diaphragm;  E,  reflector;  F,  coarse  adjustment;  <?,  fine  adjustment; 
H,  substage  condensing  apparatus;  /,  nose-piece. 

animal  or  vegetable  single  cell1  contains  an  easily  distinguish- 
able body,  usually  central,  called  the  nucleus,  whose  function 

1  See  frontispiece  for  an  example  of  cell.  Nearly  all  living  cells  are  com- 
parable to  these  leukocytes. 


24  GENERAL  MORPHOLOGY 

it  is  to  control  the  cell  activities,  while  the  space  between 
this  body  and  cell  wall  is  occupied  by  protoplasm  or  cyto- 
plasm, a  soft,  spongy,  or  gelatinous  matter,  which  under 
very  high  magnification  seems  to  be  made  up  of  a  delicate 
meshwork,  within  the  spaces  of  which  a  fluid  lies.  The 
nucleus  is  a  denser  body  usually  separated  from  the  cyto- 
plasm by  a  distinct  wall  or  membrane,  and  when  mashed  out 
is  seen  to  consist  of  a  skein  of  coarse  threads.  Into  the  cyto- 
plasm the  nourishment  of  the  cell  passes.  Of  bacteria,  either 
in  their  natural  condition  or  stained  for  examination,  only 
the  nucleus  and  the  wall  can  be  seen,  the  intervening  layer 
being  exceedingly  thin. 


oo 


a 

oo 


00 

<bo 


c 

FIG.  2. — a,  staphylococci;  6,  streptococci;  c,  diplococci;  d,  tetrads;  e,  sarcinse. 

(Abbott.)  : 


In  shape,  bacteria  are  either  spherical,  called  cocci  (sing., 
coccus),  or  straight  rods,  called  bacilli  (sing.,  bacillus),  or 
curved  rods,  called  spirilla  (sing.,  spirillum).  Each  shape 
has  slight  variations,  such  as  the  flattening  of  the  sides 
when  two  organisms  are  apposed.  The  spirilla  are,  perhaps, 
subject  to  more  variations  than  the  others,  extending  from 
a  simple  comma  shape  to  that  of  a  long,  wavy  spiral  when 
looked  at  from  the  side.  These  last  are  in  reality  corkscrews, 
as  they  twist  in  three  planes.  In  size  microorganisms  vary 


REPRODUCTION  25 

considerably.  Perhaps  a  proper  conception  of  some  organ- 
isms can  be  obtained  when  one  considers  that  to  cover  one 
square  inch  in  single  layer  it  would  require  6,250,000,000 
influenza  bacilli,  a  very  small  organism,  or  45,000,000  anthrax 
bacilli,  a  bacterium  of  moderate  size.  Bacteria  are  measured 
in  terms  of  microns.  The  metric  unit,  a  micron,  equals 
about  2TtfFo  of  an  inch. 


-w 

v-<>$ 


o-r  %• 

d  e  f 

FIG.  3. — a,  bacilli  in  pairs;  6,  single  bacilli:  c  and  d,  bacilli  in  threads;  e  and  /, 
bacilli  of  variable  morphology.     (Abbott.) 


M 
«  6  c  d 

FIG.  4. — a  and  d,  spirilla  in  short  segments  and  longer  threads — the 
so-called  comma  forms  and  spirals;  6,  the  forms  known  as  spirochetfe; 
c,  the  thick  spirals  sometimes  known  as  vibrios.  (Abbott.) 


REPRODUCTION. 

Bacteria  multiply  by  a  simple  dividing  of  their  proto- 
plasm. The  spherical  organisms  divide  much  as  one  cuts 
an  apple  through  the  poles,  the  divided  halves  rapidly 
assuming  the  shape  of  the  mother  cell.  The  rods  and  spirals 
divide  by  simple  transverse  pinching  in  at  about  the  middle 
of  their  long  axis. 


26  SPECIAL  CHARACTERS 

The  new  forms  may  leave  each  other. or  may  adhere  in 
more  or  less  characteristic  groupings,  which  are  taken  advan- 
tage of  in  their  study  and  identification.  Thus  cocci  may 
form  pairs  or  chains,  and  are  known  as  diplo-  or  streptococci. 
Again,  the  spheres  may  produce  irregular  grape-like  bunches 
or  staphylococci.  These  develop  in  only  two  planes.  Division 
may  occur  in  the  third  plane  so  that  packets  or  cubes  of 
cells  result,  called  sarcince.  Among  the  rod-shaped  bacilli 
long  chains  may  be  formed  by  a  continuous  development  in 
the  same  plane. 

A  single  bacterial  cell  will  divide  about  every  twenty 
minutes,  and  Fischer  says  that  from  one  organism  16,000,- 
000,000  may  develop  in  a  single  day  on  suitable  medium. 
Fortunately,  however,  foodstuff  is  used  up  in  the  course  of 
multiplication  and  the  waste  products  of  nutritional  activity 
accumulate  so  that  the  enormous  growth  of  bacteria  is 
limited.  Bacteria  can  no  better  live  in  the  presence  of  their 
excretions  than  can  animals. 

SPECIAL  CHARACTERS. 

The  cell  sometimes  surrounds  itself  by  an  envelope  or 
capsule  outside  its  natural  wall,  and  this  is  taken  advantage 
of  in  identification.  It  is  particularly  well  developed  on 
bacteria  when  in  or  lately  removed  from  animal  tissues  upon 
which  they  have  been  growing.  The  exact  function  or 
importance  of  these  capsules  is  not  known. 

Some  bacteria  are  able  to  move  from  place  to  place  in  a 
fluid  medium,  and  are  called,  therefore,  motile.  This  is  due 
to  the  presence  of  extremely  fine  filamentous  extensions 
from  the  cell  wall,  which  upon  microscopic  examination 
look  like  wavy  hairs.  These  are  called  flagella  (sing.,  flagel- 
lum).  They  are  arranged  either  at  one  end,  both  ends,  or 
around  the  whole  surface  of  the  cell.  They  propel  the 
bacterium  by  a  quick  waving  or  lashing  motion. 

When  bacteria  are  subjected  to  conditions  unfavorable 


SPECIAL  CHARACTERS 


27 


for  their  life  they  undergo  various  changes  of  size  and  shape, 
none  of  which  are  very  characteristic  except  the  so-called 
spore  formation.  By  this  is  meant  the  concentration  of  the 


FIG.  5. — Capsule  stained  by  Hiss's  method.    Rhinoscleroma  bacillus. 
X  1000.     (Thro.) 


**•>"» 


.*-» 


% ,- 


FIG.  6. — Bacilli  showing  one  polar  flagellum.     (Park.) 

vital  powers  and  some  of  the  physical  constituents  of  the 
bacterial  cell  within  a  very  small,  homogeneous,  highly 
light- refractive  body  which  is  resistant  to  deleterious  agencies 
and  which  may  bear  little  or  no  resemblance  to  the  parent 


28 


SPECIAL  CHARACTERS 


organism.  These  spores  are  not  to  be  considered  as  evidences 
of  reproduction,  but  merely  as  a  resting  or  resistance  stage. 
When  conditions  of  life  suitable  to  the  normal  appearance 
of  the  bacterium  are  resumed  the  spore  will  develop  into  the 
same  kind  of  organism  as  that  from  which  it  came.  This 


FIG.  7. — Bacilli  showing  multiple  flagella.     (Park.) 


FIG.  8. — Unstained  spores  in  slightly  distended  bacilli.    (The  spores  are  the 
light  oval  spaces  in  the  heavily  stained  bacilli.)      (Park.) 

spore  forming  is  seen  among  bacilli  and  spirilla,  probably 
never  among  the  cocci.  As  a  rule,  only  one  spore  is  found 
in  each  bacterial  cell.  These  spore  formations  assist  in  identi- 
fication. The  practical  importance  of  spores  is  that  they 
resist  the  agencies  quickly  fatal  to  the  adult  or  vegetative 


SPECIAL  CHARACTERS  29 

forms.  Bacteria  in  their  ordinary  development  are  said  to 
be  vegetating,  and  we  must  differentiate  between  the  vege- 
tative stage  and  the  spore-forming  stage. 

Protozoa  (sing.,  Protozoan). — Protozoa  are  single-cell  ani- 
mals of  protean  shape.  They  vary  in  size  from  that  of 
the  smallest  bacterium  to  nearly  one-quarter  of  an  inch  in 
length.  The  cell  wall  varies  considerably;  it  may  be  well 
formed  and  have  an  appreciable  thickness  or  be  merely  an 
immeasurable  line.  Their  cytoplasm,  unlike  that  of  bacteria, 
is  usually  far  in  excess  of  the  nucleus.  It  is  sometimes  homo- 
geneous, at  other  times  full  of  granules,  septa,  or  a  dividing 


FIG.  9. — Unstained  spores  in  distended  ends  of  bacilli.     (Park.) 

meshwork.  The  nucleus  is  a  complex  body  varying  from  a 
simple,  bladder-like  mass  to  a  dense  and  intricately  wound 
skein.  The  vital  activity  of  the  protozoan  cell  seems  to  lie 
in  a  small  body,  usually  in  the  protoplasm,  but  originating 
from  the  nucleus,  called  the  centrosome.  Protozoa  move 
by  several  methods:  Some  possess  short,  delicate,  hair-like 
projections  from  the  wall,  which  exhibit  a  slow,  wavy  motion. 
These  are  cilia.  Others  have  one,  two,  or  three  long  coarser 
threads,  the  flagella  (sing.,  flagellum),  arising  from  various 
parts  of  the  structure  and  producing  locomotion  by  a  thrash- 
ing or  whip- like  motion.  Perhaps  the  simplest  and  surely 
the  most  primitive  form  of  motion  is  produced  by  what  are 


30  CHEMICAL  AND  PHYSICAL  PROPERTIES 

called  pseudopods  or  false  feet,  a  phenomenon  characteristic 
of  the  amebse.  This  is  a  pushing  out  or  budding  of  a  portion 
of  the  cell  wall  into  which  the  cytoplasm  of  the  protozoon 
flows,  enlarging  the  false  foot  until  it  embraces  all  the  con- 
tents of  the  cell.  The  space  formerly  occupied  by  the  proto- 
zoon is  vacated,  the  cell  having  moved  to  a  position  directed 
by  the  pseudopod.  In  some  protozoa  a  portion  of  the  body 
has  muscular  power  and  drives  the  organism.  Again,  a  por- 
tion of  the  cell  wall  may  be  fitted  with  a  sucking  apparatus, 
serving  either  to  drive  the  protozoon  or  to  attach  it  to  another 
body.  Protozoa  gain  their  food  by  simple  absorption  through 
the  wall  or  by  possessing  definite  vacuoles  or  openings  for 
this  purpose.  Excretion  takes  place  the  same  way. 

Reproduction  may  occur  by  simple  division  as  in  bacteria. 
Protozoa  may  divide  by  simple  budding  with  breaking  off  of 
the  smaller  piece  similar  to  the  first  stages  of  the  pseudopod. 
The  higher  protozoa  go  through  a  complicated  process  of 
division  such  as  is  seen  in  the  higher  animal  cells,  or  there 
may  be  male  and  female  elements  with  conjugation. 


CHEMICAL  AND  PHYSICAL  PROPERTIES. 

Bacteria. — Chemically  the  bacterial  body  is  composed 
chiefly  of  water  (80  to  90  per  cent.),  the  remaining  part 
being  made  up  of  protein  (see  below),  fatty  matters,  includ- 
ing waxes,  a  trace  of  the  carbohydrates  (sugars  and  starches), 
and  inorganic  material.  The  cellulose  supposed  to  be  charac- 
teristic of  vegetable  cells  is  present  in  very  small  quantities, 
if  at  all.  The  largest  part  of  the  solid  matter  is  comparable 
to  the  organic  substances  which  form  the  most  important 
foodstuff  for  animals,  the  proteins.  Chlorides  and  phos- 
phates of  the  lighter  metals  form  the  inorganic  salts. 

The  wall  of  the  bacterial  cell  permits  the  passage  of  fluids 
containing  foodstuff,  and  is  therefore  comparable  to  the 
wall  of  other  vegetable  and  animal  cells. 


PROTOZOA  31 

Protozoa. — The  chemical  composition  is  probably  like  that 
of  bacteria,  although  little  is  known  of  it.  Their  vital  activi- 
ties are  influenced  by  physical  conditions,  as  is  the  case 
with  all  animate  beings.  They  require  moisture  for  their 
full  development,  but  may  live  for  indefinite  times  when  it 
is  at  a  minimum.  A  definite  temperature  is  demanded  by 
each  species  or  genus  for  its  full  activity.  They  are  suscep- 
tible to  high  degrees  and  remain  quiescent  in  nature  in  the 
cold  for  a  long  time.  Desiccation  of  the  germinating  forms 
is  usually  fatal,  but  when  in  sporulation  or  encystment, 
drying  is  more  easily  withstood.  Light  is  not  absolutely 
essential  for  the  growth  of  protozoa,  but  they  are  usually 
attracted  or  repelled  by  it;  that  is,  few  if  any  are  indifferent 
to  luminosity. 


CHAPTER  III. 

GENERAL  BIOLOGY,  INCLUDING  THE 

CHEMICAL  CHANGES  WROUGHT 

BY  BACTERIA. 

Bacteria. — The  bacteria  with  which  the  physician  is  chiefly 
concerned  as  disease-producing  are  but  a  very  small  number 
when  compared  with  the  multitude  of  species  in  nature. 
The  lay  mind  is  apt  to  consider  any  germ  as  noxious,  but 
instead  of  this  it  can  be  said  that  without  the  activity  of  many 
saprophytes,  life  on  the  earth  would  soon  be  extinct.  Animals 
require  organic  material  from  plants  for  their  nourishment, 
but  their  cells  do  not  possess  the  power  to  put  together 
(synthesize)  elementary  substances  necessary  for  their  own 
complex  cell  composition.  Bacteria  have  the  power  both  of 
breaking  down  and  building  up;  that  is,  they  may  reduce 
some  compounds  to  their  elements  or  build  up  elements  into 
more  complex  substances. 

Perhaps  the  most  striking  examples  of  this  property  are 
to  be  found  among  the  earth  organisms,  some  of  which  break 
down  organic  matter  into  ammonia  and  liberate  nitrogen, 
others  then  taking  up  this  gas  from  the  atmosphere  and 
combining  it  with  other  elements  in  a  form  that  plants  can 
assimilate. 

The  products  of  their  breaking  down  and  building  up  are 
utilized  by  plants  and  are  presented  to  animals  as  food  in 
such  a  form  that  the  animals  can  use  them  for  their  cell 
needs.  It  is  not  the  purpose  of  this  book  to  dwell  upon  this 
abstract  matter  of  general  biology,  but  the  principles  of  the 
activities  of  non-pathogenic  bacteria  can  well  be  seen  in 
those  inhabiting  the  intestines. 
(32) 


BACTERIA  33 

It  may  be  possible  for  a  human  being  to  live  without 
bacteria  in  the  alimentary  tract,  but  some  of  those  present 
are  beneficial  in  effect.  A  perfectly  healthy  young  animal 
may  be  born  without  bacteria  in  the  intestines,  but  organ- 
isms soon  gain  entrance  with  air  and  food,  since  practically 
no  object  in  the  world  of  life  is  free  of  them.  The  ordinary 
saprophytes  of  the  intestinal  tract  assist  in  making  fats 
more  easily  assimilable  and  destroy  some  of  the  pathogenic 
bacteria. 

Bacteria  require  for  their  life  moisture  some  degree  of 
heat  and  a  variety  of  foodstuffs. 

The  amount  of  moisture  is  of  little  importance  provided 
sufficient  is  available  to  make  up  the  physical  bulk  of  the 
organism  and  assist  in  the  passage  of  foodstuffs  through 
the  cell  wall.  The  substances  used  by  bacteria  in  nutrition 
are  dissolved  or  suspended  in  water.  Temperature  require- 
ments are,  however,  more  exact,  and  every  class  has  its  own 
preferred  degree.  Those  which  commonly  inhabit  the  animal 
body  require  a  temperature  of  98°  F.  (37°  C.),  while  those 
living  naturally  in  soil  or  water  thrive  best  at  60°  to  70°  F. 
(15°-21°  C.).  Foodstuffs  must  contain  the  same  substances 
as  for  the  growth  of  other  plants,  but  the  organisms  which 
infest  the  animal  body  grow  most  luxuriantly  when  animal 
tissue  or  fluid  is  present. 

The  reaction  of  the  material  upon  which  they  are  growing 
is  of  no  small  importance.  Nearly  all  bacteria  live  best 
when  the  medium  is  about  neutral  or  of  faintly  alkaline  or 
acid  reaction.  All  need  carbon,  oxygen,  nitrogen,  hydrogen, 
and  salts.  Some  organisms  cannot  live  in  the  presence  of 
free  oxygen,  but  obtain  it  as  they  need  it  by  breaking  up, 
or  reducing,  substances  containing  this  element.  These  are 
called  anaerobic  bacteria,  such  as  the  tetanus  bacillus.  Micro- 
organisms that  can  live  in  the  presence  of  atmospheric 
oxygen  are  called  aerobic;  most  pathogenic  forms  have  this 
power. 

The  foodstuffs  presented  to  bacteria  are  seldom  in  a  pure 
3 


34  GENERAL  BIOLOGY 

state,  so  that  the  power  of  breaking  up  the  material  on  which 
they  are  existing  into  the  elements  necessary  for  the  life  of 
the  cell  has  to  be  done  by  some  process  of  cellular  activity. 
To  do  this,  bacteria  form  what  are  called  enzymes  or  ferments. 
An  enzyme  or  ferment  is  a  product  capable  of  changing  a 
chemical  combination  without  itself  entering  into  the  prod- 
uct of  this  change.  The  bacterial  enzymes  are  comparable 
to  the  enzymes  found  in  the  digestive  juices  of  the  human 
alimentary  canal.  There  are  many  kinds  of  ferments,  each 
having  the  power  of  breaking  up  certain  chemical  substances. 
There  are  ferments  splitting  up  sugars  and  starches  and  fats 
and  proteids,  and  the  result  of  this  splitting  is  simpler  in 
composition  than  the  substance  split,  thus  making  it  easier  of 
use  as  food.  The  ferment  activity  of  bacteria  is  just  like 
that  of  yeasts  which  are  used  in  the  industries,  especially 
that  of  spirituous  liquor-  making.  In  this  case  the  organisms 
and  their  enzymes  are  capable  of  splitting  sugar  with  the 
production  of  ethyl  alcohol,  and  specific  species  or  strains 
are  kept  by  vineyards,  distilleries,  and  breweries  for  the 
peculiar  kind  of  fermentation  desired. 

Some  bacteria  have  the  property  of  producing  light  (phos- 
phorescent bacteria  on  sea  water),  and  many  form  coloring 
matter  both  in  nature  and  when  grown  artificially  (colored 
mould  on  preserves). 

Some  of  these  saprophytes  living  in  the  intestine  have  the 
power  of  destroying  certain  pathogens  that  gain  entrance. 
Metchnikoff  found  that  certain  bacteria  produced  so  much 
acid,  chiefly  lactic  acid,  that  many  other  bacteria  could  not 
live  in  their  presence.  He  took  advantage  of  this  to  assist 
in  the  treatment  of  certain  cases  of  putrefaction  in  the 
intestinal  tract.  It  happens  that  some  intestinal  bacteria, 
perhaps  under  the  stimulation  of  irregularity  of  function, 
may  produce  too  much  fermentation  of  sugars  and  starches 
or  too  great  breaking  down  of  the  most  important  food- 
stuffs, the  proteids.  From  this  improper  breaking  down  and 
absorption  of  its  products  comes  the  so-called  intestinal 


PROTOZOA  35 

intoxication.1  MetchnikofFs  experiments  have  shown  that 
the  high  acid  reaction  produced  by  certain  saprophytes,  the 
lactic  acid  germs  in  particular,  is  inimical  to  the  producers 
of  this  disturbance.  In  practice,  therefore,  cultures  of  these 
bacteria  are  administered  by  mouth. 

Other  activities  of  bacteria  and  their  enzymes  are  seen 
in  the  precipitation  and  curdling  of  cream  known  as  cheese. 
Again,  the  specific  flavor  of  tobacco  and  opium  for  the  pipe 
is  due  to  bacteria.  In  the  production  of  indigo  and  in  the 
preparation  of  hides  for  tanning,  bacterial  enzymes  play  an 
important  part. 

Bacteria  serve  a  useful  purpose  in  the  disposal  of  sewage 
and  food  wastes.  There  is  a  large  group  of  them  that  digests 
organic  material  to  a  simple  soluble  form,  reducing  the  bulk 
of  matter  discarded  by  man  and  animals  as  waste,  at  the 
same  time  destroying  pathogenic  germs.  This  last  action 
is  done  chiefly  by  robbing  the  disease-producing  organisms 
of  oxygen  and  producing  so  much  acid  that  life  for  them  is 
impossible.  This  is  well  seen  in  the  septic  tank  process  of 
sewage  disposal,  a  method  of  storing  waste  for  some  days 
to  allow  the  above  processes  to  occur. 

The  disease-producing  powers  of  bacteria  might,  in  a 
philosophical  sense,  be  looked  upon  as  carrying  out  the  same 
scheme  of  removing  a  certain  number  of  human  beings  and 
animals  so  that  the  world  will  not  become  overcrowded.  At 
all  events  the  action  of  bacteria  in  the  universe  is  beneficial 
in  very  many  ways,  and  as  an  enemy  they  are  to  be  looked 
upon  as  only  one  of  the  many  forces  with  which  life  must 
contend,  yet  without  which  life  would  be  impossible. 

Protozoa. — Of  the  saprophytes  of  protozoa  practically 
nothing  is  known.  Protozoa  are  parasitic  either  by  the 
mechanical  irritation  caused  by  their  presence  or  by  taking 
their  nutriment  to  the  damage  of  their  host.  Malaria 

1  Auto-intoxication  is  a  term  sometimes  given  to  this  condition,  but  it  is 
incorrect  and  should  be  limited  to  disease  due  to  some  functional  disorder 
of  digestion. 


36  GENERAL  BIOLOGY 

organisms,  for  example,  may  block  capillaries  and  shut  off 
blood  supply,  although  they  also  disturb  the  nourishment  of 
the  tissues  further  by  destroying  red  blood  cells,  which  carry 
oxygen.  For  optimum  development  they  require,  as  in  the 
case  of  bacteria,  moisture  and  a  suitable  reaction,  but  rather 
a  higher  temperature  and  more  complicated  food,  as  a  rule. 


CHAPTER  IV. 

METHODS  OF  STUDYING  MICROORGANISMS- 
STERILIZATION  BY  HEAT. 

LABORATORY  TECHNIC. 

IN  the  study  of  microscopic  beings  it  has  been  necessary 
to  elaborate  a  special  technic  which  will  supply  the  require- 
ments of  life.  Before  the  epoch-making  work  of  Koch  it  was 
necessary  to  cultivate  microorganisms  upon  broth  or  bread, 
and  there  was  little  known  as  to  the  exact  composition  of  the 
medium.  Koch  showed  how  to  control  the  growth  of  bacteria 
in  the  laboratory.  To  Pasteur  and  Kohn  credit  also  is  due 
for  the  standardizing  of  the  foodstuffs  upon  which  bacteria 
are  cultivated.  Let  us  assume  that  we  have  been  given  a 
culture  of  bacteria  to  study.  Since  the  identification  of 
species  is  not  a  part  of  a  nurse's  duty  it  is  not  necessary  to 
discuss  the  separation  of  many  germs  in  a  mixture.  Bacteria 
are  transferred  from  one  place  to  another,  as,  for  example, 
from  one  culture  tube  to  another  or  to  a  glass  slide,  by  means 
of  a  piece  of  platinum  wire  set  into  a  handle.  This  metal 
will  withstand  great  heat  and  can  be  sterilized  in  the  flame 
of  a  Bunsen  burner  after  every  using.  The  Bunsen  burner 
is  an  apparatus  so  arranged  that  air  is  thoroughly  mixed 
with  the  gas  and  the  mixture  is  completely  burned.  Starting 
out  with  the  material  from  which  this  single  organism  comes, 
the  bacteriologist  spreads  it  on  a  glass  slide  and  colors  it  by 
certain  aniline  or  vegetable  dyes,  of  which  there  is  a  large 
number.  It  is  practically  impossible  to  identify  certainly 
any  bacterium  by  a  simple  examination  of  a  stained  prepara- 
tion under  the  microscope.  The  observer,  however,  does 

(37) 


38         METHODS  OF  STUDYING  MICROORGANISMS 


form  a  tentative  opinion  as  to  its  probable  nature,  and  pro- 
ceeds to  introduce  some  of  the  material  into  a  nutrient 
medium  which  he  considers  best  adapted  to  its  development. 
Among  these  are  broth,  milk,  potato,  coagulated  blood  serum, 
and  broth  stiffened  (when  cool)  with  gelatin  and  the  Japanese 
moss,  agar-agar.  These  foodstuffs,  called  media  for  short 
(sing.,  medium),  are  kept  in  test-tubes  or  flasks.  The  worker 


FIG.  10.— Culture  tubes.     (Park.) 

may  also  spread  into  flat  glass  plates  (Petri  plates)  some  of 
this  solid  medium,  agar-agar  or  gelatin,  in  order  first  to  see  in 
what  form  the  germs  will  grow  as  "  colonies,"  and,  secondly, 
to  see  that  only  one  kind  of  colony,  therefore  only  one  kind 
of  germ,  is  present  (Fig.  11).  In  other  words,  he  wishes  to 
know  if  his  culture  be  "pure."  This  means  of  obtaining  a 
pure  culture  depends  upon  the  fact  that  from  each  single 
organism  smeared  upon  a  plate  only  one  kind  of  colony  of 


LABORATORY  TECHNIC 


39 


organisms  will  develop.  It  is  the  custom  to  put  all  material 
to  be  examined  upon  plates  of  nutrient  medium  to  start 
with,  by  which  process  the  worker  at  once  has  before  him 
evidence  to  show  how  many  kinds  of  bacteria  are  present  as 
well  as  the  means  of  isolating  pure  cultures  after  the  first 
inoculation.  These  tubes  and  plates  are  placed  at  body 


FIG.  11. — Showing  certain  macroscopic  characteristics  of  colonies. 
Natural  size.     (Abbott.) 


temperature  (98°  F.  or  37.5°  C.)  in  the  incubator.  An 
incubator  is  a  doubly  insulated  metal  box,  heated  by  gas  or 
electricity,  and  controlled  by  an  automatic  device  by  which 
the  temperature  is  kept  constantly  where  desired.  Practically 
all  pathogenic  bacteria  develop  best  at  this  temperature. 
The  bacteria  of  the  soil  and  water  grow  best  at  about  70°  F. 


40         METHODS  OF  STUDYING  MICROORGANISMS 

or  20°  C.  After  these  tubes  and  plates  have  been  "  incubated" 
for  twenty-four  to  forty- eight  hours  the  bacteriologist 
observes  them  and  takes  note  of  the  evidences  of  growth. 
He  will  make  stained  preparations  for  microscopic  observa- 
tion and  note  the  morphology  of  the  plant.  Many  stains  are 
in  use  for  demonstrating  various  characteristics.  He  will 
also  prepare  what  is  known  as  a  "hanging  drop."  This 


* 


» 

i 

•    -  • 
. 
-• 

j 

. 


FIG.  12. — Platinum  needle  and  loop.     (Park.) 

consists  of  a  drop  of  fluid  broth  culture  upon  a  thin  cover 
inverted  over  a  depression  ground  into  a  glass  slide  (Fig.  14). 
He  will  discover  from  this  preparation  under  the  microscope 
the  presence  of  motility  and  the  manner  of  division  of  the 
bacteria.  From  his  tube  cultures  he  chiefly  finds  out  whether 
the  bacteria  develop  enzymes.  To  solid  media  (agar-agar) 
he  may  add  various  sugars  to  discover  the  fermentative 
powers  of  the  bacterium.  The  fermentative  powers  may  also 


LABORATORY  TECH  NIC  41 

be  observed  when  the  germs  grow  upon  bouillon  containing 
the  sugars.  This  broth  is  placed  in  an  apparatus  called  a 
fermentation  tube,  so  arranged  that  the  percentage  of  sugar 


FIG.  13. — Method  of  transferring  cultures  from  one  tube  to  another. 
(Hiss  and  Zinsser.) 

broken  up  by  the  bacteria  can  be  estimated.  When  he  shall 
have  made  all  his  observations  he  will  sum  up  his  results  and 
identify  according  to  the  classification  of  bacteriologists. 


FIG.  14. — Hollow  slide  with  cover-glass.     (Park.) 

The  presence  of  bacteria  is  searched  for  in  pus  and  dis- 
eased tissues  by  making  a  smear  from  the  fluid  or  affected 
part  upon  glass  slides  and  treating  it  with  certain  dyes. 


42         METHODS  OF  STUDYING  MICROORGANISMS 

Before  the  dyestuff  is  applied  the  smear  must  be  fixed  by 
heat  or  alcohol  or  formaldehyde.  This  is  for  the  purpose 
of  killing  the  albuminous  material,  keeping  it  exactly  as  it 
was  when  removed  from  the  body,  and  rendering  it  suscep- 
tible of  taking  up  and  permanently  retaining  stains,  a 
property  living  tissues  and  fluid  possess  to  a  very  limited 
degree.  Once  fixed  and  stained,  examination  will  reveal 
the  bacteria  present,  and  the  observer  can  form  an  opinion 
of  the  probable  nature  of  the  infection.  Reference  is  fre- 
quently made  in  the  text  to  Gram's  stain,  and  it  is  desirable 
that  the  reader  be  familiar  with  the  term  and  its  significance. 
It  is  a  combination  of  anilin  oil,  water,  and  gentian  violet, 
which  stain  can  be  fixed  into  some  bacteria  by  after-treatment 
with  iodin  solution,  so  that  alcohol  will  not  wash  it  out.  The 
test  is  of  great  importance  in  determining  certain  species. 

Animal  Inoculation. — Another  method  of  studying  bacteria 
is  by  injecting  them  into  susceptible  animals.  Thus  can  be 
discovered  their  power  of  producing  disease,  its  severity, 
called  virulence,  and  the  nature  of  their  action.  When  the 
presence  of  bacteria  in  morbid  matter  cannot  be  demonstrated 
by  stain  or  by  cultural  methods,  it  may  sometimes  be  shown 
by  injecting  the  suspected  material  into  animals.  If  the 
animal  fall  sick  or  die  one  can  then  obtain  cultures  of  the 
germs  for  study.  The  value  of  this  method  of  discovering 
bacteria  is  increased  by  the  development  of  changes  in  the 
animal's  organs  peculiar  to  certain  germs.  Thus  the  tubercle 
bacillus,  an  organism  not  easy  to  find  by  direct  examination, 
produces  definite  alterations  of  organs  and  special  kinds  of 
inflammation  by  which  its  presence  is  indicated  and  from 
which  it  can  be  obtained.  This  is  also  true  for  other  bacteria 
— streptococci,  anthrax,  and  glanders  bacilli. 

Protozoa. — The  study  of  protozoa  varies  according  to  the 
source.  The  parasite  of  malaria  may  be  found  by  direct 
microscopic  examination  of  the  fresh  blood.  This  is  also 
true  of  the  organism  of  sleeping  sickness.  The  protozoa 
causing  dysentery  require  the  maintenance  of  •  a  definite 


STERILIZATION  43 

temperature  for  a  long  time,  and  this  is  achieved  by  the  use 
of  an  object  slide  surrounded  by  warm  water.  These  organ- 
isms are  cultivated  artificially  only  with  great  difficulty, 
and  the  use  of  special  stains  is  required  for  the  purpose  of 
practical  clinical  diagnosis. 


STERILIZATION. 

For  a  better  understanding  of  the  technic  of  laboratory 
procedure,  the  preparation  of  the  foodstuffs  or  media  on 
which  bacteria  thrive  will  be  briefly  considered.  They  are 
prepared  from  meat  or  its  extracts,  a  substance  called  pep- 
tone, and  salt,  and  adjusted  to  a  suitable  reaction  of  weak 
alkalinity,  according  to  carefully  worked-out  formulae,  which 
are  the  result  of  long  experimentation.  They  are  stored  or 
distributed  in  glassware,  which  is  of  the  non-corrosive  type. 
This  glassware  is  cleaned  with  soap  and  water,  sand  or  alcohol, 
and  rinsed  with  distilled  water.  It  is  then  sterilized  by  hot 
air.  The  glassware  and  media  are  sterilized  because  bacteria 
are  ubiquitous,  and  apparatus  and  foodstuffs  wholly  free  from 
microorganisms  are  necessary  in  bacteriological  technic.  In 
no  other  way  can  one  be  sure  of  obtaining  germs  in  pure 
culture,  that  is,  only  one  kind.  After  the  medium  has  been 
put  into  the  glassware,  steam  sterilization  is  used;  dry  heat 
is  ineffectual  and  destroys  the  medium.  The  best  method 
of  sterilization  is  by  the  autoclave  or  pressure  boiler,  since 
all  organisms  are  killed  by  one  atmosphere  of  pressure  to  the 
square  inch  in  addition  to  the  ordinary  atmospheric  pressure. 
Because  of  the  delicacy  of  some  of  the  nutrient  media  it  is, 
however,  necessary  to  sterilize  these  at  the  usual  pressure  of 
the  atmosphere  in  streaming  steam.  For  this  purpose  a 
double- jacketed  boiler  with  the  steam  introduced  into  the 
inner  chamber  (Arnold  steam  sterilizer)  is  used. 

While  this  sufficiently  indicates  the  use  of  sterilization  for 
the  preparation  of  food  for  bacteria,  a  few  words  upon  sterili- 


44         METHODS  OF  STUDYING  MICROORGANISMS 


zation  in  general  are  necessary.    This  term  is  usually  reserved 
for  the  killing  of  bacteria  by  means  of  heat,  either  dry  or 


FIG.  15. — Erlenmeyer       FIG.  16. — Petri  dish.         FIG.  17. — Fermenta- 
flask.  tion  tube. 


\k 


A  B 

FIG.  18. — Autoclave,  pattern  of  Wiesnegg:   A,  external  appearance; 
B,  section. 

moist.     For  the  killing  of  bacteria  by  other    means  see 
Chapter  V. 


STERILIZATION  45 

The  most  widely  applicable  and  efficient  physical  agent 
for  sterilization  is  heat.  A  certain  amount  of  heat  is  necessary 
for  the  life  of  bacteria,  but  there  are  certain  temperatures 
beyond  which  they  cease  to  live.  While  38°  C.  or  98.5°  F. 
is  their  optimum  or  most  suitable  temperature,  they  find  it 
increasingly  difficult  to  live  as  the  temperature  rises  to  50°  C. 
or  122°  F.  Beginning  there  and  extending  to  62°  C.  or  144° 
F.  the  commoner  pathogenic  organisms  are  killed  by  ten 
minutes'  exposure.  For  example,  the  typhoid  bacillus  dies 


1 


FIG.  19. — Arnold  steam  sterilizer. 

when  heated  to  56°  C.  or  133°  F.  for  ten  minutes,  and  the 
pneumonia  coccus  at  52°  C.  or  126°  F.  for  ten  minutes.  The 
tubercle  bacillus  is  much  more  resistant  and  requires  from 
ten  to  twenty  minutes'  exposure  at  70°  C.  or  158°  F.,  varying 
directly  with  the  density  of  the  material  in  which  it  happens 
to  be  exposed.  The  spore-forming  organisms  are  character- 
ized by  a  vastly  greater  resistance.  This  is  due  to  the 
peculiar  property  of  spores  of  resisting  deleterious  agencies. 
Low  temperatures  are  much  less  destructive  than  high 


46         METHODS  OF  STUDYING  MICROORGANISMS 

ones.  The  typhoid  and  diphtheria  organisms  may  resist  200° 
below  zero  C.  or  —300°  F.,  while  some  of  the  more  delicate 
organisms  quickly  die  at  zero. 

In  sterilization  that  method  is  chosen  that  will  do  the 
least  damage  to  any  object  to  be  conserved.  Simple  boiling 
should  be  undertaken  whenever  practicable,  and  immersion 
for  five  minutes  in  boiling  water  will  destroy  the  vegetative 
forms  of  all  bacteria.  For  spores,  however,  at  least  of  the 


FIG.  20. — Laboratory  hot-air  sterilizer. 


disease-producing  kind,  two  hours  is  necessary.  It  is  advis- 
able to  add  1  per  cent,  of  sodium  carbonate  to  the  water.  This 
assists  in  killing  of  spores,  and  metal  objects  are  not  so  apt  to 
rust.  This  simple  boiling  for  ten  minutes  is  sufficient  for 
dry  cleansed  syringes,  trays,  dishes,  and  surgical  instruments 
in  the  absence  of  infective  material  known  to  contain  spores. 
Sterilization  in  live  steam  is  the  most  practical  method  of 
killing  bacteria,  as  it  can  be  conducted  in  the  kitchen.  In 
the  laboratory  it  is  done  by  the  Arnold  sterilizer  (Fig.  19). 


STERILIZATION  47 

It  is  the  custom  to  employ  what  is  called  fractional  sterili- 
zation. This  method  is  the  exposure  of  the  material  to  be 
disinfected  to  the  temperature  of  100°  C.  or  212°  F.,  which 
is  the  temperature  reached  by  the  steam  in  the  inner  chamber, 
for  fifteen  minutes  on  three  successive  days.  On  the  first 
occasion  vegetative  forms  are  killed  and  the  spores  remaining 
are  permitted  to  pass  into  the  vegetative  state  overnight. 
On  the  second  occasion  these  will  then  be  killed.  A  third 
exposure  ensures  sterility.  The  exposure  of  fifteen  minutes  is 
considered  to  begin  when  the  steam  is  up  and  the  thermom- 
eter registers  100°.  The  foregoing  method  is  practicable 
for  dressings  and  rubber  gloves  but  the  newer  types  of  oper- 
ation room  autoclaves,  those  with  air-drying  appliances,  are 
to  be  preferred  whenever  practicable.  For  sterilization  of 
objects  not  injured  by  pressure  the  boiler  or  autoclave 
should  be  used,  as  it  destroys  spores  with  certainty.  The 
principle  of  this  apparatus  is  that  steam  is  admitted  into  the 
sterilizing  chamber,  the  air  having  been  expelled  by  heating 
of  the  walls  and  displacement  by  the  entering  steam.  When 
no  air  is  present  the  pressure  within  the  apparatus  rises  and 
steam  penetrates  all  permeable  objects.  When  the  steam 
escapes  and  air  enters,  moisture  is  absorbed  and  the  objects 
become  dry.  By  this  means  as  much  as  two  extra  atmos- 
pheric pressures  can  be  run  up,  which  will  be  equivalent  to 
34.5°  C.  or  74°  F.  above  the  boiling-point.  After  starting 
up  steam  the  apparatus  should  never  be  tightly  closed  at  the 
safety-valve  until  all  air  is  expelled.  This  method  is  particu- 
larly adapted  to  the  sterilization  of  dressings  and  infected 
cast-off  clothing.  Hot  air  is  suitable  for  dried  glassware  and 
articles  injured  by  moisture,  and  can  be  used  for  domestic 
sterilization  by  exposing  the  articles  in  the  household  oven. 
It  is  less  efficient  than  moist  heat.  This  is  due  to  the  fact 
that  organic  substances  are  less  easily  coagulated  in  a  dried 
condition.  Spores  are  more  resistant  also,  as,  for  example, 
the  anthrax  spore,  which  requires  an  exposure  of  three  hours 
at  140°  C.  or  284°  F.  dry  heat.  Hot,  dry  air  penetrates  less 


48         METHODS  OF  STUDYING  MICROORGANISMS 

easily  than  hot  moisture.  Burning  is  the  best  of  all  methods, 
and  should  be  used  for  everything  which  can  be  spared, 
handkerchiefs,  dressings,  and  objects  like  magazines  from  the 
sick  room. 

The  two  thermometric  scales  are  explained  as  follows: 

F.  =  Fahrenheit,  the  ordinary  scale  used  in  this  country.  Water  just  at 
the  freezing-point  registers  32°  F.,  while  just  at  the  boiling-point  registers 
212°  F.  The  zero  has  no  relation  to  physical  changes. 

C.  =  Centigrade,  the  French  system.  Water  just  at  the  freezing-point 
is  0°  C.,  and  just  at  boiling-point  is  100°  C. 

The  100°  in  the  Centigrade  scale  is  equal  to  the  180°  between  32°  and 
212°  in  the  Fahrenheit  scale. 

To  change  one  system  to  the  other  proceed  as  follows: 

From  Fahrenheit  to  Centigrade:  Given  degree  F.  — 32-i-9X5  =  same 
degree  in  Centigrade  scale.  Example:  50°  F.  -32  =18 -=-9  =2X5  =10. 
Therefore50°F.=10°C. 

From  Centigrade  to  Fahrenheit:  Given  degree  C.  -i-5  X9+32  =  same 
degree  in  Fahrenheit  scale.  Example:  10°  C.  ^5=2X9=18+32=50°  F. 


CHAPTER  V. 

DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 
AND  THEIR  PRACTICAL  USE. 

IT  has  been  shown  how  bacteria  can  be  killed  by  heat, 
and  now  the  chemical  methods  of  destroying  infective 
material  will  be  discussed,  and  how  this  may  be  done  prac- 
tically. Chemicals  either  in  solution  or  as  gas  are  supposed  to 
kill  bacteria  by  one  of  several  methods.  The  whole  bacterial 
body  may  be  destroyed  or  the  protoplasm  may  be  entered  by 
a  diffusion  of  the  substance  through  the  cell  wall  with  conse-  / 
quent  coagulation  or  solution.  It  is  said  also  that  the  rapid 
withdrawal  of  water  absorbed  by  some  salts  may  be  fatal  to 
the  microorganism. 

There  is  some  confusion  as  to  the  terms  used  for  chemical 
bacteria  killing,  and  for  this  reason  it  may  be  well  to  start 
out  with  Park's  classification.  (1)  Attenuation  is  when  the 
pathogenic  or  vital  functions  of  the  bacteria  are  temporarily 
diminished.  (2)  Antiseptic  action  is  when  the  bacteria  are 
not  able  to  multiply  but  are  not  destroyed;  they  will  repro- 
duce when  suitable  conditions  for  life  are  restored.  (3) 
Incomplete  sterilization  or  disinfection  is  when  the  vegetative 
forms  but  not  the  spores  are  destroyed.  (4)  Sterilization  or 
disinfection  is  when  both  vegetative  and  spore  forms  are 
destroyed;  this  implies  also  the  destruction  of  any  products 
of  bacteria  capable  of  producing  disease. 

Practical  disinfection  must  provide  not  only  for  superficial 
action  but  also  for  penetrative,  and  a  disinfectant  should  be 
selected  which  will  act  as  deeply  as  possible.  Formaldehyde 
gas  or  its  solution  has  a  high  penetrating  power  and  is  there- 
fore commonly  used  for  the  disinfection  of  rooms,  mattresses, 
4  (49) 


50       DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

and  clothing  after  infectious  diseases.  Simple  air  disinfection 
is  of  practically  no  value,  since  disease  viruses  do  not  live 
long  in  the  air  but  may  settle  upon  surfaces  where  they  can 
be  killed  either  by  gaseous  disinfectants  or  direct  application 
of  germicides.  All  disinfection  is  rendered  more  efficacious 
by  a  good  cleansing  and  a  liberal  supply  of  "elbow  grease." 

A  chemical  is  tested  for  its  antibacterial  properties  in 
several  ways,  chief  among  which  is  the  immersion  of  some  of 
the  pure  bacterial  growth  in  solution  of  various  strengths 
of  the  chemicals. 

Some  of  the  individual  disinfectants  are: 

Bichloride  of  Mercury  (corrosive  sublimate). — This  is 
soluble  in  16  parts  of  cold  water.  One  part  in  100,000  inhibits 
the  growth  of  most  bacteria.  In  twice  that  strength  many 
kinds  are  killed  in  a  few  minutes.  Spores  are  destroyed  in 
1  to  500  solution  in  water  within  one  hour.  In  order  to  obtain 
the  best  results  with  this  corrosive  sublimate  it  is  necessary 
to  have  an  acid  reaction,  for  which  reason  most  of  the  tablets 
now  on  the  market  are  made  up  with  an  acid  having  no  effect 
upon  the  mercury  salt.  The  acid  reaction  is  especially 
demanded  when  the  material  to  be  disinfected  is  pus,  blood, 
feces  or  the  like,  substances  containing  albumin  which  com- 
bines with  the  mercury  and  renders  it  inert.  It  is  wise  to 
use  a  strength  of  1  to  500  for  one-half  hour  when  any  such 
organic  material  is  present.  The  disadvantages  of  bichloride 
are,  beside  that  mentioned  above,  that  it  corrodes  metals  and 
is  rather  hard  on  the  skin.  It  is  well  to  add  some  coloring 
matter  to  the  solution  for  the  purpose  of  identification,  since 
this  is  a  rapidly  acting,  corrosive,  deadly  poison.  Great  care 
should  be  used  in  keeping  the  tablets  and  solutions,  as  many 
accidents  have  occurred.  Being  odorless  it  attracts  no 
attention. 

Silver  Nitrate. — Park  says  that  this  salt  has  one-fourth 
the  value  of  the  preceding  as  a  disinfectant,  but  nearly  the 
same  value  in  restraining  bacterial  growth.  It  is  not  a  very 
practical  disinfectant,  because  of  its  destructive  action  on  the 


CHLORIDE  OF  LIME  51 

skin  and  fabrics,  but  it  can  be  used  with  value  in  diphtheria. 
Solutions  should  be  freshly  prepared  in  1-2  per  cent,  strength. 

Copper  Sulphate. — This  chemical  is  potent  against  typhoid 
in  water  in  the  presence  of  little  organic  material  in  the 
strength  of  1  to  400,000  in  twenty- four  hours.. 

Sodium  Hydroxide  (caustic  soda). — This  substance  is  very 
destructive  to  fabric  and  to  the  skin,  but  kills,  in  the  strength 
of  1  to  100,  vegetative  bacteria  in  a  few  minutes,  or  spores  are 
destroyed  by  4  per  cent,  solution  in  forty-five  minutes. 

Sodium  Carbonate. — This  chemical,  advantageous  for 
boiling  instruments,  kills  vegetative  forms  in  5  per  cent, 
solution  very  quickly,  or  spores  in  boiling  water  in  about 
five  minutes. 

"Chloride  of  Lime"  (chlorinated  lime). — This  chemical  is 
also  known  as  bleaching  powder.  There  is  a  difference  of 
opinion  as  to  its  composition.  Its  power  depends  upon  the 
liberation  of  free  chlorine  gas,  which  rapidly  disappears  when 
the  lime  is  exposed,  so  that  the  dry  material  must  be  kept 
covered  and  solutions  prepared  as  needed.  It  is  destructive 
to  fabrics.  A  1  per  cent,  solution  will  kill  all  non-spore- 
bearing  organisms  in  five  minutes,  and  a  5  per  cent,  solution 
destroys  spores  in  one  hour.  Calcium  hydroxide,  made  by 
adding  water  to  quicklime,  is  efficient  against  typhoid  bacilli 
in  feces  when  a  20  per  cent,  solution  is  added  to  thoroughly 
mixed  feces  in  equal  parts  and  exposed  one  hour. 

There  have  lately  been  developed  several  disinfecting  sub- 
stances of  especial  value  to  surgeons,  depending  upon  chlorin 
for  their  action.  They  are: 

Dakin's  solution,  a  solution  of  chlorinated  lime,  sodium 
carbonate,  and  sodium  bicarbonate  so  mixed  that  it  has  an 
alkalinity  of  0.45  per  cent.  When  this  solution  comes  in  con- 
tact with  tissue,  hypochlorous  acid  and  chlorin  are  formed  and 
the  antiseptic  action  occurs.  Necrotic  tissue  is  dissolved  and 
hidden  groups  of  bacteria  are  exposed.  The  chlorin  upon 
which  the  antiseptic  action  depends  is  evanescent,  so  that  the 
fluid  must  be  renewed  frequently.  The  fluid  should  be  pro- 


52       DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

tected  from  heat  and  light,  since  these  factors  destroy  its 
power.  Skin  surfaces  must  be  protected  by  vaseline,  for  the 
solution  is  very  irritating. 

Chloramin-T  is  another  chemical  dependent  upon  chlorin 
for  its  action,  but  is  more  stable,  less  toxic,  and  irritating 
than  Dakin's  solution,  so  that  it  may  be  used  in  stronger 
percentage  (2  per  cent.)-  It  is  applied  directly  to  wounds  or 
even  to  mucous  membranes. 

Dichloramin-T  is  a  third  chlorin  antiseptic.  It  is  not 
stable  and  must  be  suspended  and  dissolved  in  an  oily 
menstruum  previously  saturated  with  chlorin;  chlorinated 
eucalyptol  or  paraffin  oil  (a  suitable  form  being  called 
chlorcosane)  are  used  for  this  purpose.  This  substance  is 
used  for  highly  infected  wounds  or  for  the  nasal  cavity  by 
application  on  gauze  or  by  spraying.  It  is  not  very  irritating 
to  the  skin. 

Carbolic  Acid  or  Phenol. — This  is  a  crystalline  solid  which 
softens  when  exposed  to  the  air.  It  is  soluble  in  15  parts  of 
water.  It  must  be  thoroughly  mixed  with  material  to  be 
disinfected.  It  is  not  destructive  to  fabrics  or  colors.  It 
acts  best  at  about  the  body  temperature.  It  is  not  much 
affected  by  the  presence  of  organic  substances.  A  5  per  cent, 
solution  kills  spores  in  a  few  hours,  and  1  to  1000  inhibits  the 
growth  of  all  bacteria  and  may  be  considered  as  an  antiseptic; 
3  per  cent,  solutions  kill  the  pus  cocci  in  one  minute. 

Cresols. — These  are  thick,  sticky,  brown  fluids  related  to 
carbolic  acid.  They  make  a  milky  emulsion  with  water.  The 
best-known  ones  are  tricresol,  creolin,  and  lysol.  The  two 
latter  are  probably  the  best,  as  they  mix  with  water  fairly 
well.  All  these  substances  in  5  per  cent,  emulsion  kill  the 
ordinary  bacteria  within  three  minutes  and  the  spore-formers 
within  an  hour. 

Other  Disinfectants. — Ordinary  alcohol  kills  vegetative 
forms  in  a  few  hours.  A  70  per  cent,  alcohol  is  perhaps  the 
most  potent.  It  has  lately  been  shown  that  for  surface 
disinfection  no  method  is  superior  to  10  per  cent,  iodin  in 


SULPHUR  DIOXIDE  53 

70  per  cent,  alcohol.  Practical  surgical  work  seems  to  indi- 
cate that  for  skin  disinfection  before  operation  all  bacteria 
are  destroyed  in  the  epidermis.  Some  defenders  of  this 
method  maintain  that  its  penetrating  powers  exceed  any 
other  known  practical  disinfectant.  The  method,  while 
undoubtedly  excellent,  must  remain  for  a  while  sub  judice 
before  one  can  accept  this  statement.  Chloroform  kills 
vegetative  bacteria  and  restrains  spores,  even  in  small 
quantities.  Ordinary  soap  is  a  good  disinfectant,  particularly 
by  its  solvent  power  on  the  simple  organic  substances.  Its 
effect  is  increased  by  the  addition  of  common  washing 
soda. 

Acids. — The  strong  mineral  acids  are  not  practical  disin- 
fectants, but  nevertheless  are  very  efficient.  Boric  acid  kills 
the  less  resistant  organisms  in  a  2  per  cent,  solution,  but  only 
after  some  hours'  exposure. 

Gaseous  Disinfectants. — There  are  only  three  of  practical 
value.  They  are  sulphur  dioxide,  oxygen  from  hydrogen 
dioxide,  and  formaldehyde.  Chlorin  is  not  included  here 
because  it  is  seldom  used  in  its  pure  state,  since  it  is  highly 
poisonous  and  destructive;  it  is,  however,  eminently  effi- 
cient. (See  p.  51.) 

Sulphur  Dioxide. — Sulphur  dioxide  is  used  for  hospitals, 
apartments,  and  ships,  and  is  especially  well  suited  to  the 
destruction  of  rats  and  insects.  It  is  more  efficient  when  there 
is  considerable  moisture  in  the  air.  When  conditions  are 
suitable  for  disinfection,  anthrax  bacilli  in  the  vegetative 
condition  are  destroyed  in  thirty  minutes  when  there  is  1 
volume  per  cent,  of  the  gas  in  the  given  space.  "  Four  pounds 
of  sulphur  burned  for  each  1000  cubic  feet  will  give  an  excess 
of  gas."  Some  water  should  be  sprayed  in  the  room  or  an 
open  vessel  containing  water  should  be  there.  It  has  been 
suggested  that  the  sulphur  candles  of  commerce  be  burned, 
resting  on  a  brick  in  a  bucket  of  water.  The  gas,  while  very 
efficient,  cannot  be  used  as  a  general  disinfectant  because  of 
its  destructive  action  upon  colors,  fabrics,  and  metals. 


54       DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

Dioxide  of  Hydrogen. — A  2  per  cent,  solution  of  the  pure 
substance  will  kill  anthrax  spores  within  three  hours.  In 
20  per  cent,  solution  it  kills  vegetative  bacteria,  pus  cocci 
and  the  like  in  a  few  minutes.  Its  activity  depends  upon  the 
liberation  of  free  oxygen.  It  should  be  kept  tightly  sealed, 
since  it  easily  gives  up  this  gas. 

This  substance  has  been  widely  used  in  the  great  European 
war  in  the  treatment  of  gas  bacillus  infection,  its  beneficial 
effects  being  widely  commented  upon  and  attributed  to  the 
liberation  of  oxygen  in  the  tissues  with  bactericidal  effect. 
It  seems  to  me  that  this  cannot  be  all  the  reason,  as  this  gas 
is  soon  utilized  by  the  tissues.  A  much  more  probable  expla- 
nation is  that  the  liberation  of  bubbles  tears  the  tissues  into 
large  webbed  meshes  and  allows  other  disinfectants  free  play 
or  permits  a  penetration  of  atmospheric  oxygen  inimical  to 
the  anaerobic  germs. 

Formaldehyde.— This  is  a  gas,  but  is  most  commonly  seen 
as  a  solution  ordinarily  known  under  its  trade  name  formalin. 
This  contains  from  35  to  40  per  cent,  of  the  gas  and  also  some 
wood  alcohol.  The  gas  has  an  affinity  for  many  organic 
substances,  am6ng  them  some  of  the  dyes,  but  fabrics  are 
not  affected.  Of  the  metals,  iron  and  steel  are  attacked  after 
long  exposure  in  the  presence  of  moisture.  By  reason  of  its 
affinity  for  organic  substances  it  is  a  good  deodorizer  and 
disinfectant  chiefly  because  it  forms  new  insoluble  odorless 
compounds. 

It  is  not  very  irritant  when  taken  into  the  stomach,  but 
its  vapors  cause  considerable  annoyance  in  the  eyes,  nose, 
and  mouth.  The  lower  animals  resist  it  considerably,  but 
insects  are  not  affected.  It  is  more  effective  in  the  presence 
of  moisture  and  when  the  temperature  is  high,  up  to  120°  F. 
If  these  conditions  cannot  be  obtained  the  exposure  must  be 
longer.  Two  and  one- half  per  cent,  by  volume  of  the  aqueous 
solution  or  1  per  cent,  by  volume  of  gas  are  sufficient  to  des- 
troy fresh  virulent  cultures  of  the  common  non-spore-bearing 
bacteria  in  a  few  minutes. 


PRACTICAL  APPLICATION  OF  DISINFECTION      55 

PRACTICAL  APPLICATION  OF  DISINFECTION. 

Stock  Solutions. — As  given  by  Park  these  can  be  made 
as  follows :  6  ounces  of  carbolic  acid  in  1  gallon  of  hot  water — 
this  is  about  a  5  per  cent,  solution.  It  is  milky  at  first  and 
must  be  stirred  thoroughly.  The  addition  of  a  small  amount 
of  glycerin  keeps  the  carbolic  acid  in  solution  and  probably 
assists  in  disinfection,  in  part  by  absorbing  water,  in  part 
by  making  a  coating  on  objects  and  holding  the  phenol. 

Bichloride  solution :  60  grains  of  pulverized  bichloride  and 
2  tablespoonfuls  of  common  salt  to  1  gallon  of  hot  water  = 
1  to  1000.  Store  in  glass  or  earthen  vessels.  Agate  will 
answer.  It  is  well  to  color  the  liquid  or  to  have  a  prominent 
label  indicating  poison. 

Milk  of  lime :  1  quart  of  dry,  freshly  slaked  lime  to  4  or  5 
quarts  of  water.  Lime  is  slaked  by  pouring  a  small  quantity 
of  water  on  a  lump  of  quicklime.  The  lime  becomes  hot 
and  crumbles,  and  as  the  slaking  is  completed  a  white 
powder  results. 

Formalin  solution:  1  part  of  formalin  to  10  of  water  is 
equivalent  to  5  per  cent,  of  carbolic  acid. 

Cleansing  of  Skin. — For  this  purpose  a  1  to  1000  carbolic 
or  1  to  1000  bichloride  should  be  used,  allowing  it  to  act 
for  at  least  two  minutes.  Following  this  there  should  be 
scrubbing  with  soap  and  water  with  a  soft  brush.  It  is 
unwise  to  roughen  the  skin  with  stiff  bristles.  The  newer 
methods,  using  iodin  alcohol,  require  only  simple  soap  and 
water  washing  and  then  a  few  applications  of  the  solutions 
to  the  skin  to  be  disinfected,  allowing  each  application  to 
dry  before  proceeding. 

Fabrics. — Soiled  fabrics  should  be  soaked  in  carbolic, 
formalin,  or  bichloride  in  this  order  of  preference  for  at  least 
two  hours.  Mattresses  should  be  exposed  to  the  sun  or  re- 
moved by  health  authorities  for  disinfection.  After  soaking 
infected  goods  in  these  solutions  they  should  be  boiled  for  at 
least  twenty  minutes,  preferably  with  soap.  Materials  from 


56       DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

the  sick-room  should  never  be  carried  to  other  parts  of  the 
building  in  a  dry  state. 

Utensils. — Utensils  should  be  soaked  in  the  solutions  and 
then  boiled. 

Urine,  Feces,  and  Sputum. — Urine,  feces,  and  sputum  should 
be  received  in  glass,  earthen,  or  agate  vessels  already  con- 
taining carbolic  acid  solution,  milk  of  lime,  or  formalin,  and 
they  should  be  allowed  to  remain  for  at  least  one  hour.  It  is 
well  to  cover  the  vessel.  In  the  absence  of  disinfectants, 
discharges  should  be  burned  or  boiled  for  one-half  hour.  The 
solid  masses  of  feces  should  be  broken  up  in  order  to  permit 
the  proper  penetration  of  solutions. 


FIG.  21. — Sanitary  spit-cups. 

Tuberculous  Sputum. — Perhaps  nothing  is  so  important 
as  the  disinfection  of  tuberculous  sputum,  as  it  is  the  chief 
means  of  the  transmission  of  tuberculosis.  It  should  be 
received  preferably  in  a  pasteboard  cup  within  a  metal  holder, 
the  former  being  burned,  the  latter  frequently  disinfected, 
either  over  a  flame  or  by  immersion  in  carbolic  acid  solution. 
It  may  be  caught  in  metal  or  agate  cups  containing  carbolic 
or  milk  of  lime  solution.  If  caught  in  handkerchiefs  they 
should  be  burned.  The  hands  must  be  washed  in  a  disin- 
fectant after  catching  sputum  in  a  handkerchief. 


DISINFECTION  OF  ROOMS  AND  HOUSES  57 

Water-closets  and  Sinks. — They  should  not  receive  infective 
materials  until  they  shall  have  been  thoroughly  disinfected. 
To  disinfect  sinks  and  water-closets,  chlorinated  lime,  cresols, 
and  carbolic  acid  are  the  best. 

Disinfection  of  Rooms  and  Houses. — The  disinfection  of 
rooms  and  their  contents,  while  not  necessarily  the  nurse's 
duty,  deserves  some  mention.  In  case  of  infectious  dis- 
ease, physical  cleaning  must  be  left  until  after  chemical 
disinfection  shall  have  been  done.  It  is  then  carried  out  on 
the  ordinary  plan  of  house-cleaning.  The  practical  methods 
of  house-disinfection  today  have  narrowed  down  to  formal- 
dehyde. There  are  many  forms  of  apparatus  and  several 
methods  of  producing  this  gas,  but  whatever  the  procedure, 
certain  conditions  must  be  observed.  The  temperature  of 
the  air  in  the  room  must  not  be  less  than  100°  F.,  and  there 
should  be  a  high  percentage  of  moisture.  The  most  common 
method  now  used  for  the  production  of  formaldehyde  gas  is 
the  mixture  of  1  pint  of  commercial  formalin  and  10  ounces 
of  small  crystals  of  potassium  permanganate  in  an  open 
vessel  for  each  1000  cubic  feet  of  air  space.  These  are  usually 
mixed  in  the  center  of  the  room  in  a  tall  metal  case  of  some 
sort,  surrounded  by  water,  which  serves  the  purpose  of  catch- 
ing any  of  the  mixture  which  bubbles  over  or  extinguish- 
ing fire  which  sometimes  occurs  spontaneously.  Another 
efficient  method  of  liberating  formaldehyde  is  the  heating  of 
a  mixture  of  10  per  cent,  glycerin  in  formalin  in  a  copper 
vessel;  this  is  simpler  than  the  above  and  just  as  efficacious. 
The  cracks  of  doors  and  windows  are  always  sealed  by 
pasting  strips  of  paper  over  them  and  the  room  left  sealed 
for  twenty -four  hours;  this  saves  much  of  the  vapor  for  disin- 
fection and  protects  inmates  of  other  parts  of  the  house.  Any 
remaining  odor  may  be  displaced  by  sprinkling  ammonia 
about. 

The  transmission  of  disease  by  books,  especially  in  libraries 
and  institutions,  is  a  possibility  but  not  a  great  menace. 
Only  such  reading  matter  as  can  be  destroyed  or  readily 


58       DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

disinfected  should  be  allowed  in  the  room  with  a  case  of  the 
more  serious  infections.  Books  in  large  numbers  are  disin- 
fected by  exposing  them  in  a  chamber  to  which  formaldehyde 
vapor  can  be  admitted.  In  small  numbers  they  may  be  ren- 
dered harmless  by  sprinkling  pure  formalin  solution  on  every 
second  page  and  laying  them  in  a  tightly  closed  drawer. 

Instruments. — Instruments,  including  syringes,  may  be 
boiled  for  five  minutes  in  a  1  per  cent,  solution  of  washing 
soda.  Knives,  however,  should  be  kept  in  alcohol.  Gauze 
should  be  sterilized  at  120°  C.  or  248°  F.  and  15  pounds' 
pressure. 

Many  hospitals  use  gauze  over  and  over  again.  The  prin- 
ciple in  such  reclamation  is  that  the  gauze  must  be  sterilized 
after  such  cleaning  that  no  spore  formers  or  other  highly 
resistant  viruses  remain  hidden  in  clots  or  masses  of  pus. 
Gauze  dressings  should  be  received  in  plain  soapy  water  in 
which  they  are  washed  with  gloved  hands;  they  are  then 
rinsed  in  several  changes  of  clean  water,  sorted  and  sterilized 
in  an  autoclave.  If  preferred  they  can  be  received  in  weak 
cresol  solution  but  not  in  bichloride.  Dressings  from  such 
diseases  as  anthrax,  actinomycosis,  tetanus,  gas  bacillus 
infection,  and  symptomatic  anthrax  would  better  not  be 
re-used. 

Pasteurization. — This  consists  in  the  heating  of  a  substance, 
milk  usually,  to  a  temperature  below  the  boiling-point,  usually 
140°  F.  or  56°  C.,  which  kills  the  non-spore-bearing  bacilli, 
and  holding  there  for  a  few  minutes.  It  is  then  cooled  as 
rapidly  as  possible  to  a  point  at  which  bacteria  do  not  usually 
multiply,  that  of  the  ice-chest.  This  does  not  sterilize  the 
substance,  but  in  the  case  of  milk  may  render  it  more  likely 
to  spoil  afterward  if  not  properly  taken  care  of. 

Sunlight. — A  most  admirable  disinfectant  is  sunlight. 
Direct  sunlight  will  eventually  kill  all  bacteria,  and  it  is  wise 
to  expose  materials  from  the  sick-room,  whether  from  an 
infectious  case  or  not,  to  as  much  sunlight  as  possible. 


CHAPTER  VI. 

THE  RELATION  OF  BACTERIA  TO  DISEASE- 
IMMUNITY. 

THE  difference  between  saprophytes  and  parasites  has 
already  been  emphasized  and  incidentally  it  has  been  learned 
that  the  latter  may  for  a  short  time  lead  a  life  comparable 
to  that  of  the  former.  The  organisms  that  produce  disease, 
pathogenic,  are  everywhere,  particularly  in  the  crowded  life 
of  cities.  Not  only  are  they  on  the  objects  of  our  environment, 
but  within  the  entrances  to  the  body.  Sometimes  organisms 
are  found  in  the  mouth  and  nose  which  are  classed  as  patho- 
genic. Certain  organisms  are  present  invariably  in  the 
alimentary  canal,  which  under  proper  circumstances  can  pro- 
duce disease.  It  is  often  difficult,  therefore,  to  determine 
precisely  how  a  bacterium  enters  the  body  and  produces  the 
disease,  because  it  is  evident  that  some  factors  other  than 
the  simple  presence  of  microorganisms  are  necessary  to 
develop  what  is  termed  sickness.  A  disease  might  be  fairly 
well  described  as  the  subjective  (experienced  by  the  patient) 
and  objective  (perceived  by  the  physician)  expression  of  the 
forces  exerted  by  the  bacteria  and  the  defence  presented  by 
the  body. 

These  two  forces  must  now  be  considered,  and  following 
the  natural  sequence,  bacteria  will  be  traced  in  their  usual 
seats  upon  and  within  the  human  body,  in  their  course  past 
the  primary  defences  and  their  manner  of  awakening  the 
secondary  or  peculiar  immunity  resistances  which  the  human 
system  presents. 

Bacteria  gain  entrance  to  the  body  by  introduction  through 
an  abraded  surface  of  the  skin  or  mucous  membranes.  The 

(59) 


60  RELATION  OF  BACTERIA   TO  DISEASE 

delicacy  of  the  latter  renders  infection  through  them  quite 
easy.  They  may  go  in  through  the  intestinal  tract  and  be 
absorbed  by  its  wall.  They  may  go  in  through  the  tonsils, 
larynx,  or  trachea.  In  exposure  to  cold  with  the  congestion 
and  sensitiveness  of  the  larynx  produced  thereby  we  have  an 
opportunity  for  the  absorption  of  bacteria.  Not  all  bacteria 
can  enter  by  all  ways  and  produce  disease.  The  pus  cocci,  if 
swallowed,  are  destroyed  by  the  gastric  juice,  while  typhoid 
bacilli  usually  pass  the  stomach  uninjured.  Typhoid  bacilli 
rubbed  into  the  skin  would  be  followed  by  no  disease,  but  pus 
cocci  so  applied  would  cause  boils.  Most  of  the  secretions 
and  excretions,  except,  of  course,  the  feces,  may  be  said  to  be 
mildly  inhibit! ve  to  bacterial  growth.  The  defences  of  the 
body  to  a  local  introduction  of  bacteria  depend  upon  the 
healthiness  of  the  skin  and  mucous  membranes.  The  resist- 
ance offered  has  been  found  to  be  due  to  a  power  supplied  by 
the  blood  serum  This  is  .discussed  later.  Any  physical 
condition  such  as  a  burn  or  wound  reducing  the  healthy 
trim  of  the  body  renders  invasion  easier.  Injury  and  intoxi- 
cation materially  favor  the  activity  of  bacteria  either  pre- 
viously within  the  individual  or  introduced  at  the  time. 
Normal  bodily  resistance  is  impaired  by  excessive  hunger 
and  thirst,  by  exposure  to  cold  and  wet,  or  by  prolonged 
muscular  or  mental  strains. 

Conditions  resulting  after  the  entrance  of  bacteria  into  the 
body  may  be  defined  as  follows:  Infection  is  best  considered 
as  the  presence  of  disease- producing  germs  and  the  evidence 
of  their  effects.  Intoxication  is  the  condition  due  to  the 
poisons  elaborated  by  bacteria.  Bacteremia  is  the  mere 
presence  of  bacteria  in  the  blood  while  septicemia  is  the  circu- 
lation of  bacteria  and  their  products  in  the  blood,  with  some 
involvement  of  all  the  organs  in  the  body.  Pyemia  is  similar 
to  the  last  but  includes  the  production  of  many  abscesses 
throughout  the  body.  Fever  may  be  described  as  a  disturb- 
ance by  bacterial  poisons  of  the  mechanism  in  the  brain 
which  controls  the  heat  of  the  body. 


BACTERIAL  TOXINS  61 

Some  bacteria  merely  multiply  in  the  body  and  exert  their 
effect  simply  by  their  mechanical  presence  without  any 
peculiar  poison.  Others  have  the  power  of  elaborating  poisons 
which  are  specific  or  individual  a'nd  whose  effect  is  added  to 
that  of  the  bacterial  bodies.  The  latter  form  the  larger 
percentage,  and  it  is  with  them  we  shall  deal  chiefly.  The 
ability  of  bacteria  to  cause  disease  is  spoken  of  as  their 
r/nilt'nci'.  Each  individual  kind  of  bacterium  produces  only 
one  form  of  disease,  and  always  that  one  form.  In  the  early 
history  of  pathological  bacteriology  Koch  elaborated  certain 
rules  or  postulates  by  which  the  relation  of  bacteria  to  disease 
is  determined.  They  are  essentially  that  the  same  bacterium 
should  always  be  found  in  the  same  clinical  disease,  produce 
this  disease  when  injected  into  animals,  be  recovered  again 
from  the  animals,  and  retain  its  biological  characters.  By 
this  means  the  peculiar  expression  of  bacterial  disease  has 
been  found,  and  thus  it  becomes  possible  to  separate  those 
diseases  which  are  wholly  due  to  the  bacteria  themselves  and 
those  principally  arising  from  the  bacterial  poisoning. 

Bacterial  Toxins. — Diphtheria  is  a  disease  wherein  the 
bacteria  reside  and  grow  on  a  free  surface,  such  as  the  pharynx; 
but  their  poisons  are  absorbed  and  carried  in  the  blood  stream, 
thus  producing  the  peculiar  symptoms  of  the  disease.  If, 
however,  this  toxin  is  taken,  entirely  free  of  diphtheria  bacilli, 
and  injected  into  animals,  the  same  results  can  be  obtained  so 
far  as  the  symptoms  are  concerned.  This  is  likewise  true  of 
tetanus.  For  the  development  of  typhoid  fever  and  septi- 
cemia  it  is  necessary  that  the  bacteria  themselves  should 
circulate  in  the  blood  stream.  The  reason  for  this  is  that 
while  the  poisons  of  the  diphtheria  bacilli  are  soluble  in  fluids 
and  separable  from  the  germs,  the  poisons  of  the  typhoid 
bacillus,  for  instance,  remain  within  the  body  of  the  germ  and 
are  only  effective  when  the  cell  dies  and  disintegrates.  The 
former  poisons  are  called  extracellular  toxins  and  the  latter 
infr(treHnIar  toxins  or  cti(1oto.rinft.  In  practice  the  word  toxin 
unqualified  means  extracellular  toxins,  while  intracellular 


62  RELATION  OF  BACTERIA   TO  DISEASE 

poisons  are  specifically  called  endotoxins.  Some  bacteria 
(cholera  for  example)  develop  both  kinds. 

The  local  gross  effects  of  bacterial  invasion  are  expressed 
in  inflammation,  which  is  greatest  in  those  which  act  by  their 
mechanical  presence  in  a  confined  locality,  usually  aided  by 
some  of  the  poisons  mentioned  above. 

Bacterial  poisons,  it  might  be  said,  usually  express  some 
definite  predilection  for  special  organs  or  tissues;  for  instance, 
the  tetanus  toxins  attack  the  brain,  the  streptococci  attack 
red  blood  cells,  and  the  typhoid  bacillus  settles  in  the  lymph 
glands  of  the  small  intestines. 

Incubation. — After  bacteria  have  gained  their  foothold 
there  is  a  certain  lapse  of  time  until  their  effects  become 
evident.  This  is  the  incubation  time.  Its  length  depends 
upon  the  number  of  organisms  entering,  their  virulence,  and 
the  resistance  of  the  body. 

Mixed  Infection. — Sometimes  there  is  more  than  one  kind 
of  bacterium  in  an  infection.  This  is  called  a  mixed  infection, 
and  although  there  is  the  expression  of  both  causes,  one 
usually  predominates.  This  usually  results  from  the  entrance 
of  the  second  invader,  owing  to  the  lowered  resistance  of  the 
body  produced  by  the  first  invader. 

Transmission  of  Disease. — The  transmission  of  diseases 
from  one  individual  to  another  takes  place  in  various  ways, 
but  it  may  be  said  in  general  that  the  means  of  transference 
must  present  conditions  favorable  for  the  retention  of  viru- 
lence on  the  part  of  the  bacteria.  Some  bacteria,  notably 
gonococci  and  influenza  bacilli,  die  very  quickly  when  dried 
or  exposed  to  direct  light.  On  the  other  hand,  tubercle 
bacilli  resist  drying  and  diffuse  light  for  several  days.  Cough- 
ing and  spitting  transfer  infective  organisms  from  the  mouth 
to  the  air,  and  persons  in  the  vicinity  may  receive  them. 
Clothes  soiled  with  discharges,  both  urine  and  feces,  from 
typhoid  patients,  contain  the  bacilli  and  are  capable  of  carry- 
ing the  disease.  Scales  from  the  skin  in  the  acute  eruptive 
diseases  of  children  may  transmit  infection.  Milk  and  water 


TRANSMISSION  OF  DISEASE  63 

have  been  known  to  transmit  diphtheria,  typhoid,  scarlatina, 
and  other  conditions. 

Insects  transmit  disease  in  two  ways,  mechanically  and 
specifically.  Diseases  like  typhoid  and  tuberculosis  may  be 
transmitted  by  flies,  which  soil  themselves  on  excreta  or 
sputum  and  deposit  the  infective  matter  upon  food  or  other 
objects,  which  later  get  into  the  human  body.  Other  diseases 
probably  to  be  credited  in  this  category  are  plague  and 
diphtheria. 

In  the  other  class  of  insect- born  disease  the  transmission 
can  only  take  place  by  this  means.  Thus  malaria  is  only 
transmitted  from  the  sick  to  the  uninfected  by  the  Anopheles 
mosquito,  sleeping  sickness  only  by  the  tsetse  fly,  and  yellow 
fever  only  by  the  Aedes  mosquito.  In  these  insects  there  is  a 
development  of  the  virus  to  such  a  degree  that  it  can  be 
infective  for  an  unprotected  person,  and  for  each  disease  this 
so-called  cycle  of  development  is  necessary  for  its  further 
propagation.  None  of  the  diseases  demanding  an  insect  for 
its  spread  can  be  transmitted  by  one  person  to  another  by 
the  most  intimate  personal  contact.  .  . 

It  may  be  laid  down  as  a  law  that  with  the  exception  of 
the  few  infectious  disorders  only  carried  by  insects,  intimate 
personal  contact  is  the  most  prolific  source  of  the  spread  of 
disease.  The  objects  before  mentioned— clothing,  dishes, 
books,  utensils,  and  so  forth — called  "  fomites,"  were  formerly  ! 
believed  of  considerable  importance  in  transmitting  disease, 
but  latterly  more  weight  has  been  laid  upon  individuals  as 
carriers  of  viruses.  This  has  come  to  pass  because  it  has  been 
found  that  more  persons  contract  disease  after  having  come 
in  contact  with  persons  than  with  objects  from  sick-rooms, 
and  for  this  reason  much  room  and  object  disinfection  has 
been  stopped.  The  writer  still  thinks  that  disinfection  of  a 
room  should  be  done  before  physical  cleaning,  because  of  the 
possible  ganger  to  the  cleaners  of  such  a  room  where  the  virus 
may  lurk  in  corners  and  cervices. 


64  RELATION  OF  BACTERIA   TO  DISEASE 

Persons  suffering  with  an  infectious  disease  are,  of  course, 
the  greatest  danger  in  communication,  but  other  persons  may 
also  carry  infection.  Attendants  upon  typhoid,  diphtheria, 
or  meningitis  patients  may  carry  upon  the  hands  or  clothing 
or  in  the  mouth  and  nose,  bacteria  of  the  respective  diseases 
without  themselves  having  the  disease,  and  may  be  called 
"passive"  or  "accidental"  carriers.  Doctors  and  nurses  too 
often  are  innocently  in  this  class.  After  recovery  from  the 
acute  attacks  of  some  diseases,  notably  typhoid,  diphtheria, 
and  dysentery,  patients  frequently  carry  the  germs  for  indefi- 
nite periods;  these  are  called  "chronic  carriers."  Such 
persons  are  great  menaces  and  are  usually  controlled  by 
health  authorities  when  known,  but  as  certain  diseases  are 
endemic  among  us,  particularly  such  conditions  as  scarlatina, 
for  which  the  quarantine  is  very  rigid,  the  number  of  so-called 
"hidden  carriers"  must  be  very  great.  Inasmuch  as  very 
many  infectious  diseases  are  contracted  by  receiving  the 
virus  in  the  nose  and  throat  from  the  nasal  and  pharyngeal 
secretion  of  patients,  it  behooves  the  nurse  and  visitors  to 
know  this  and  protect  themselves.  This  is  conveniently 
done  by  the  use  of  gauze  masks  over  nose  and  mouth  worn 
both  by  patient  and  nurse,  especially  the  latter,  since  the 
former  should  not  be  made  uncomfortable  and  needs  all  the 
air  possible.  Masking  the  patient  has  the  advantage  of 
preventing  the  spread  of  the  virus  in  the  room. 

Bacteria  are  directly  the  cause  of  ptomain  poisoning, 
although  the  ones  concerned  may  not  live  within  the  body. 
Ptomain  poisoning  is  a  violent  irritation  of  the  gastro- 
intestinal tract  by  certain  poisons  produced  from  putre- 
faction of  meat  and  fish  by  bacteria.  The  foods  may  be  little 
or  not  altered  by  these  poisonous  substances  in  them.  They 
are  in  small  quantity  in  the  food,  but  are  easily  and  quickly 
absorbed.  It  is  possible  that  for  a  short  time  after  ingest  ion 
of  the  meat  the  formation  of  these  ptomains  may  continue. 
Ptomains  differ  from  toxins  in  that  they  are  formed  by 
altering  the  chemical  composition  of  the  meat  rather  than 


IMMUNITY  65 

by  any  peculiar  products  of  the  bacteria,  and  they  are  not 
specific  for  any  particular  variety  of  microorganism.  Ptomain 
poisoning  is  not  transmissible. 

IMMUNITY. 

The  resistance  offered  to  the  entrance  of  microorganisms 
into  the  body  has  already  been  referred  to,  and  now  the 
method  by  which  our  physiology  gets  rid  of  the  effects  of 
these  noxious  agents  must  be  considered.  It  is  a  well-known 
fact  that  illness  does  not  occur  every  time  pathogenic  bacteria 
gain  a  foothold  on  or  within  the  body.  Sometimes  a  small 
number  of  bacteria  overcome  the  primary  defences  and  yield 
when  the  reserve  powers  have  been  brought  into  play.  Again, 
a  low  grade  of  virulence  may  be  possessed  by  the  invaders, 
and  although  many  enter,  the  specific  disease  process  is  halted 
by  the  economy.  Moreover,  some  individuals  seem  to  be 
poor  hosts  for  certain  bacteria,  while  others  are  received 
readily.  The  general  resistance  of  the  body  to  disease  is 
spoken  of  as  immunity.  Immunity,  as  the  term  is  usually 
used,  means  that  an  individual  is  not  susceptible  to  a  disease, 
but  not  necessarily  that  he  would  not  be  infected  under  very 
severe  circumstances. 

Types  of  Immunity. — Immunity  is  classified  as  (1)  natural 
or  racial  or  species  immunity,  and  (2)  acquired  immunity, 
which  latter  has  been  further  divided  into  active  and  passive. 

Natural  immunity  is  the  condition  wherein  a  certain  disease 
does  not  occur  in  the  type  of  animal  under  consideration,  as, 
for  example,  the  dog  does  not  take  typhoid  fever  even  when 
fed  a  pure  culture  of  the  specific  germs.  There  is  also  a 
relative  natural  immunity.  Cats  present  great  resistance  to 
infection  with  anthrax. 

Racial  immunity  is 'shown  by  great  resistance  of  the  negro 
to  yellow  fever. 

There  is  also  individual  immunity,  as  shown  by  the  passing 
of  a  person  through  a  virulent  epidemic  without  the  slightest 
sign  of  illness. 
5 


66  RELATION  OF  BACTERIA   TO  DISEASE 

Acquired  immunity  is  that  resistance  which  a  person 
obtains  by  passing  through  an  attack  of  disease.  That  a 
second  attack  of  measles  or  scarlatina  or  typhoid  fever 
seldom  occurs  is  well  known.  Such  an  acquired  immunity 
is  called  active  acquired  immunity  because  the  economy  has 
had  to  work  for  its  own  protection,  and  it  is  only  good  for  the 
one  kind  of  disease,  supplying  no  protection  to  any  other  kind : 
that  is,  it  is  specific.  There  is  also  a  passive  acquired  immunity 
by  which  is  meant  that  some  protective  substances  from 
another  individual  are  added  to  the  natural  resistance  of  the 
body.  This  passive  acquired  immunity  is  very  well  shown 
in  diphtheria  when  the  serum  of  a  horse  which  has  been 
rendered  resistant  to  the  toxin  of  the  diphtheria  bacilli  is 
given  to  the  patient.  This  horse  is  said  to  possess  active 
artificial  immunity  because  it  has  been  given  the  poisons 
themselves  in  such  a  manner  that  its  blood  has  been  able  to 
develop  anti-  or  against- poisons  or  antitoxins,  strong  enough 
to  neutralize  the  toxins  of  the  diphtheria  bacilli.  This  blood 
is  suitable  to  be  transferred  to  another  individual,  and  in 
the  body  of  the  latter  offsets  the  effects  of  the  toxin  of  the 
diphtheria  bacillus.  In  other  words,  the  horse's  economy 
has  worked  actively  against  the  poison,  whereas  the  person 
receiving  the  horse's  serum  has  not  worked,  but  merely 
received  a  neutralizing  substance  from  the  horse's  serum;  it 
has  been  passive.  This  passive  immunity  is  also  seen  in  the 
treatment  of  tetanus  by  an  antiserum  (see  Antitoxins),  and 
lately  antisera  against  meningitis  and  pneumonia  have  been 
produced. 

Artificial  immunity  is  one  that  has  been  produced  inten- 
tionally by  the  physician.  The  term  may  be  correctly  applied 
to  any  form  except  the  natural  or  active  acquired  immunities, 
but  it  is  usually  reserved  for  the  various  procedures  in  experi- 
mental medicine  whereby  antiserums  or  vaccines  are  manu- 
factured. 

Anti-endotoxins. — These  bodies,  comparable  to  antitoxins, 
are  developed  in  the  blood  serum  when  the  system  harbors 


IMMUNITY  67 

bacteria  whose  pathogenic  power  depends  upon  intracellular 
poisons.  Many  kinds  of  anti-endotoxins  or  antibodies  (a 
term  embracing  antitoxins  also  but  more  commonly  used  as 
here)  are  formed.  The  important  ones  are  discussed  under 
the  Actions  of  Bacterial  Toxins  and  their  Antibodies. 

Antitoxins. — The  production  of  antitoxins  hinges  on  this 
subject.  Antitoxins  may  be  described  as  the  substances 
produced  in  the  blood  or  blood  serum  of  animals  injected  with 
the  poisons  elaborated  by  bacteria,  but  soluble  and  separable 
from  the  germ  cells.  The  toxins  used  to  make  the  injections 
into  animals  are  obtained  by  growing  the  bacteria  in  broth 
and  then  filtering  oft'  their  bodies.  They  are  distinguished 
from  the  poisons  described  in  a  preceding  paragraph  in  that 
no  destruction  of  the  germs  is  necessary  to  produce  these 
separable  toxins. 

Recapitulation. — To  recapitulate  briefly,  active  acquired 
immunity  is  produced  by  injection  of  living  bacterial  cells 
when  incapable  of  producing  disease,  or  by  their  endocellular 
poisons  or  extracellular  separable  toxins.  In  the  case  of  the 
latter  it  is  possible  to  take  from  the  blood  serum  of  the 
immune  animals  something  which  will  neutralize  the  toxins 
introduced,  in  other  words,  the  principle  involved  in  making 
of  diphtheria  and  tetanus  antitoxin.  The  former,  non-viru- 
lent germs  or  their  poisons,  is  used  now  as  the  basis  of  bacterin 
treatment. 

Action  of  Bacterial  Poisons  and  Their  Antibodies. — This 
matter  is  very  complicated  and  not  by  any  means  perfectly 
understood  by  the  most  profound  scientists.  It  is,  moreover, 
unnecessary  to  enlarge  upon  it  in  a  work  of  this  kind,  and 
tracing  the  methods  as  simply  as  possible  is  sufficient. 

The  free  soluble  toxins  stimulate  the  production  of  anti- 
toxins which  have  an  attraction  for  the  toxin,  and  for  it  only. 
Therefore  when  any  free  toxin  and  free  antitoxin  come 
together  they  combine  and  one  neutralizes  the  other. 

In  the  case  of  the  reaction  of  bacterial  cells  or  their  endo- 
toxins  the  result  is  more  complicated.  Many  substances 


68  RELATION  OF  BACTERIA   TO  DISEASE  ' 

are  formed,  again  called  anti-,  or  in  general,  antibodies. 
Three  will  be  considered:  (1)  The  antibodies  which  dissolve 
bacterial  cells;  (2)  those  which  clump  them;  and  (3)  those 
which  encourage  the  white  cells  of  the  blood  to  eat  them. 
The  substances  exist  in  minute  quantities  in  normal  blood. 

1.  Eacteriolysins . — The  first  antibodies  cause  a  dissolving 
of  the  bacterial  cells.    These  antibodies  are  called  bacterio- 
lysins  (adj.,  bacterioly tic) .     There  is  in  all  blood,  whether 
normal  or  subjected  to  immunizing  procedures,  a  substance 
called  complement,  which  makes  possible  these  combinations 
of  antibody  and  germ. 

2.  Agglutinins. — Agglutinins  are  substances  which  cause 
clumping  of  bacterial  cells,  but  do  not  dissolve  them.    They 
are  made  use  of  in  the  diagnosis  of  some  acute  fever,  notably 
in  the  Widal  reaction  of  typhoid.     (See  Typhoid  Fever.) 

3.  Opsonins. — These    are    substances    which    act    upon 
bacteria  and  prepare  them  for  consumption  by  certain  cells 
of  the  body,  especially  of  the  blood,  called  phagocytes,  a  term 
applied  because  they  have  the  power  of  devouring  foreign 
substances.     Bacteria  are  such,  and  it  is  the  task  of  these 
phagocytes  to  remove  them.    These  cells  are  also  migrating 
cells,  as  they  leave  the  blood  stream  and  wander  over  the 
body.    It  has  been  found  that  in  some  conditions  their  power 
of  consuming  bacteria  is  below  par,  and,  further,  that  if  small 
numbers  of  germs  incapable  of  producing  disease  are  intro- 
duced, the  power  of  these  cells  may  be  stimulated  for  the 
particular  kind  of  germ  introduced  and  not  for  others.    The 
bodies    producing   this    increased   eating    or   phagocytosis, 
opsonins,  are  supposed  not  to  act  upon  the  cells,  but  upon  the 
bacteria  and  make  them  more  suitable  as  food  for  the  phago- 
cytes.    These  phenomena  have  put  a  valuable  method  of 
treatment  in  the  physician's  hands.     In  subacute  localized 
disorders   particularly,    but    also    in   definitely    acute   and 
chronic  troubles,  injections  of  dead  cultures  of  the  bacteria 
responsible  for  the  condition,  are  made  beneath  the  skin. 
The  progress  of  treatment  is  followed  by  a  long  elaborate 


IMMUNITY  69 

test  of  permitting  the  leukocytes  of  the  blood  of  the  patient, 
and  as  a  control,  those  of  a  healthy  person,  to  feed  upon  the 
bacteria  in  question  in  test-tubes  kept  at  body  heat.  If  the 
number  of  germs  consumed  by  the  patient's  leukocytes  rises 
during  the*  course  of  the  treatment,  he  is  considered  as  bene- 
fitting  from  the  injections.  His  general  constitutional  con- 
dition is  closely  watched  also.  It  is  now  attempted  to  use  for 
"vaccination"  a  culture  made  from  the  patient's  disease,  the 
co-called  "autogenous  vaccine." 

Principles  of  Artificial  Immunity. — To  return  for  a  space  to 
active  immunity,  it  is  well  to  consider  here  the  basis  of  the 
present-day  bacterin  treatment.  The  ordinary  vaccination 
against  smallpox  depends  upon  the  fact  that  human  smallpox 
virus  passed  through  a  calf  for  a  number  of  times  loses  its 
power  to  produce  smallpox  in  man.  It  does  retain  power  to 
produce  a  sore,  and  this  sore  contains  sufficient  of  the  poison 
related  to  smallpox  virus  to  stimulate  in  the  vaccinated 
person  a  condition  resistant  to  the  virus  which  would  cause 
true  general  smallpox.  The  great  Pasteur  found  that  if  he 
heated  anthrax  bacilli  and  injected  them  into  sheep,  these 
animals  became  resistant  to  the  disease  anthrax.  Since  the 
time  of  Pasteur  the  management  of  the  process  which  has  been 
called  "  active  immunization"  has  been  learned.  To  accom- 
plish this  a  virus  must  be  treated  as  was  the  virus  of  smallpox, 
that  is,  it  must  be  rendered  incapable  of  causing  general 
disease,  but  it  must  not  be  so  altered  that  it  has  no  relation 
to  its  original  form.  The  living  organisms  can  be  taken  and 
subjected  to  higher  or  lower  temperatures  than  those  pre- 
ferred by  the  individual  species,  or  they  may  be  injected  into 
animals  until  they  will  merely  live  without  producing  disease. 
This  is  called  reducing  virulence.  They  may  be  killed  by  heat 
or  obtained  in  mass  and  crushed  and  ground  into  a  pulp. 
Again,  the  broth  or  other  material  upon  which  they  grow  may 
be  used  after  removing  the  bacterial  bodies  by  filtering  them 
off  through  porcelain  filters.  Having  obtained  the  virus  in  a 
reduced  state  either  dead  or  as  active  principles,  it  is  injected 


70  RELATION  OF  BACTERIA    TO  DISEASE 

beneath  the  skin  of  the  individuals  whom  it  is  desired  to 
protect,  beginning  in  minute  doses  and  increasing  the 
quantity  as  the  condition  permits.  By  this  means  the  resist- 
ance of  the  animal  or  person  to  this  particular  germ  is 
increased,  and  the  process  corresponds  to  that  of  the  produc- 
tion of  antitoxin  in  horses,  that  is,  making  an  antipoison,  or, 
as  it  is  called,  an  antibody.  The  method  just  described  is 
usually  reserved  for  the  bacteria  which  produce  intracellular 
or  endotoxins.  The  method  has  been  used  in  treating  anthrax, 
typhoid,  cholera,  etc. 

Serum  Treatment. — Since  it  is  possible  to  create  in  animals 
by  the  injection  of  bacteria  a  condition  of  the  blood  serum 
which  neutralizes  the  bacterial  poisons,  there  has  arisen  a 
specific  treatment  of  many  bacterial  diseases.  The  ones 
found  most  suitable  for  this  therapy  are  diphtheria,  tetanus, 
meningitis,  dysentery,  cholera,  streptococcus,  and  pneu- 
monia. The  antiserums  are  administered  by  injection  under 
the  skin  of  patients  and  serve  the  purposes  first  of  neutrali- 
zing any  poison  which  may  be  circulating,  of  agglutinating  free 
germs,  of  stimulating  the  phagocytes  to  devour  the  organisms, 
and  of  keeping  the  poisons  from  destroying  the  cells  of  the 
organs.  The  various  antisera  will  be  discussed  under  their 
respective  diseases. 

Anaphylaxis. — When  the  principal  constituent  of  flesh  and 
blood,  protein,  is  taken  into  the  alimentary  tract  it  is  digested 
and  absorbed  because  digestive  ferments  are  there  for  the 
purpose.  If  it  be  injected  in  solution  under  the, skin  a  fer- 
ment has  to  be  prepared  in  order  to  remove  it.  If,  now,  it 
be  injected  a  second  time  this  ferment  is  ready  and  attacks  the 
protein,  digesting  it  rapidly.  The  products  of  this  digestion 
appearing  suddenly  in  the  tissues  are  apt  to  poison  them. 
If  a  guinea-pig  be  injected  with  horse  serum  and  the  dose  be 
repeated  ten  days  later,  the  animal  will  have  dyspnea,  skin 
irritability,  and  die.  This  is  anaphylaxis,  which  we  shall  for 
our  purpose  consider  as  a  hypersusceptibility  to  protein 
matter  not  taken  in  the  normal  manner.  Some  persons 


IMMUNITY  71 

exhibit  great  susceptibility  to  antiserum  injection  because 
they  are  anaphy lactic  to  the  horse  serum,  and  while  a  few 
deaths  have  occurred,  they  usually  react  by  the  appearance 
of  "serum  sickness."  This  is  a  condition  appearing  five  to 
twelve  days  after  serum  injection,  consisting  of  skin  rashes, 
malaise,  fever,  and  albumin  in  the  urine.  The  reaction 
occurs  most  often  in  persons  who  have  asthma  when  in  the 
presence  of  horses,  and  the  physician  should  inform 
himself  as  to  this  contingency.  No  reaction  will  appear 
if  the  serum  be  given  very  slowly,  or  the  first  dose  divided 
by  a  few  hours,  or  if  a  second  injection  be  given  in  two 
to  four  days.  It  is  good  practice  to  give  always  0.5  c.c. 
under  the  skin  and  follow  with  the  remainder  of  the 
desired  quantity  four  or  five  hours  later.  If  the  reaction 
from  the  smaller  amount  is  very  severe,  the  clinician  must 
debate  the  advisability  of  further  injections.  A  single  large, 
rapid  injection  of  horse  serum  should  never  be  given  to  a 
patient,  because  it  might  make  him  susceptible  to  horses 
or  to  later  serum  injections,  against  which  a  second  dose 
within  five  days  will  protect  him.  Nurses  should  have  a 
hypodermic  of  T^-Q  gr.  of  atropin  ready  for  emergencies,  since 
this  drug  is  the  only  treatment  for  acute  symptoms  after 
antitoxin  injections.  Akin  to  the  above  mentioned  hyper- 
sensibility  of  certain  persons  to  the  presence  of  horses  are 
the  idiosyncrasies  to  pollen  exhibiting  itself  as  hay  fever,  and 
to  certain  foods,  shellfish  and  pork,  which  give  intestinal  and 
cutaneous  evidences  of  this  susceptibility.  There  is  at  present 
no  adequate  explanation  nor  satisfactory  treatment  of  these 
phenomena,  those  suffering  from  them  simply  being  obliged 
to  avoid  exposing  themselves  to  the  substances  which  intoxi- 
cate them. 

The  reader  must  not  picture  that  these  so-called  anti- 
bodies are  substances  that  can  be  handled.  They  are  invisible 
chemical  parts  of  the  serum  of  the  blood,  and  only  perceptible 
through  extremely  delicate  laboratory  procedures.  The 
present  conception  of  their  action  was  worked  out  by 


72  RELATION  OF  BACTERIA   TO  DISEASE 

Dr.  Ehrlich,  a  German  chemist  and  physicist.  His  theory, 
broadly  speaking,  assumes  a  group  of  substances  circulating 
in  the  blood  which  can  be  stimulated  to  meet  and  destroy 
invaders,  and  thereby  protect  the  body.  Besides  the  three 
methods  above  outlined,  in  which  practical  therapeutic  use 
has  been  made  of  the  known  facts  in  the  study  of  immunity, 
still  others  have  been  devised,  but  they  are  scarcely  yet  out 
of  their  experimental  stage. 


CHAPTER  VII. 

PREPARATIONS  FOR  AND  PROCURING  OF 

SPECIMENS  FOR  BACTERIOLOGICAL 

EXAMINATION. 

WHILE  it  may  not  be  the  duty  of  the  nurse  to  obtain  all 
specimens  for  bacteriological  purposes,  she  is  often  requested 
to  obtain  the  more  common  things,  and  it -behooves  her  to 
know  how  this  should  be  done. 

The  nurse  is  very  commonly  expected  to  prepare  the 
patient  for  technic  used  by  the  physician  in  procuring  speci- 
mens and  should  know  the  more  important  parts  of  such 
technic. 

Collection  of  Pus. — For  the  taking  of  cultures  of  pus  from 
abscesses  or  from  infected  surfaces  of  ulcers  or  sinuses,  an 
applicator,  usually  of  wood,  wound  with  cotton  and  sterilized 
within  a  glass  test-tube,  is  used.  The  nurse  most  commonly 
sees  this  in  connection  with  throat  cultures.  When  this 
applicator  is  passed  over  the  diseased  surface,  some  of  the 
bacteria  present  adhere  to  the  cotton.  The  adhering  particles 
are  transferred  by  the  physician  to  some  suitable  food  upon 
which  the  germs  will  grow.  In  preparing  an  exposed  infected 
surface  for  culture-taking  the  nurse  need  have  ready  only 
sterile  water  or  a  very  weak  (1  per  cent.)  boric  acid  or  sterile 
physiological  salt  solution.  Anything  stronger  may  destroy 
the  bacteria. 

Collection  of  Sputum. — Sputum  to  be  examined  for  the 
tubercle  bacillus  should  be  received  in  a  thoroughly  cleansed 
and  dried  wide-mouthed  bottle.  This  is  given  to  the  patient 
that  he  may  expectorate  directly  into  it.  When  the  specimen 
has  been  collected  by  the  patient,  the  bottle,  including  the 

(73) 


74 


BACTERIOLOGICAL  EXAMINA  TION 


inside  of  the  mouth,  should  be  wiped  off  with  a  cloth  moist- 
ened with  5  per  cent,  carbolic  acid  solution.  When  specimens 
of  sputum  are  intended  for  careful  bacteriological  cultivation, 


FIG.  22. — Showing  the  method  of  taking  a  culture  from  the  pharynx. 
(Morrow.) 


FIG.  23. — Wide-mouthed  bottle  for  collecting  sputum. 

with  the  idea  of  finding  out  what  the  causative  bacteria  in 
the  case  may  be,  the  procedure  is  different.  In  this  case  the 
bottle,  again  a  wide- mouthed  one,  must  be  plugged  with 


COLLECTION  OF  FECES  75 

raw  cotton  and  sterilized,  preferably  by  dry  heat.  Someone 
should  supervise  the  collection  of  the  specimen  and  see  that 
the  patient  spits  a  representative  (instruction  from  doctor) 
sample  directly  into  the  bottle  and  does  not  let  it  touch  the 
outside  of  the  neck.  The  part  of  the  cotton  plug  which 
extends  beyond  the  mouth  of  the  bottle  should  be  held  by 
someone  and  the  stopper  part  not  allowed  to  touch  anything 
while  out  of  the  bottle.  After  the  plug  is  replaced  the  out- 
side of  the  bottle  is  cleansed,  as  for  tuberculosis  sputum. 

The  sputum  is  an  excretion  from  the  trachea,  bronchi, 
and  lungs,  and  care  should  be  taken  that  the  specimen  col- 
lected is  such  and  not  saliva  mixed  with  posterior  nasal 
mucus.  Before  the  patient  coughs  up  the  specimen  the 
buccal  and  pharyngeal  cavities  should  be  thoroughly  rinsed 
with  warm  saline  solution;  this  removes  the  mouth  bacteria 
and  the  specimen  really  represents  the  flora  in  the  deeper 
air  passages.  In  children  it  is  necessary  to  induce  a  cough 
and  to  collect  the  sputum  on  cotton-tipped  applicators. 

Collection  of  Urine. — The  collection  of  urine  for  bacterio- 
logical purposes  must  be  done  by  catheterization,  using  all 
possible  surgical  precautions  as  to  genitalia,  hands,  and  instru- 
ments. The  urine  must  be  allowed  to  fall  from  the  end  of 
the  catheter  directly  into  a  bottle  or  test-tube  sterilized  with 
a  raw  cotton  plug,  the  plug  being  removed  when  the  col- 
lection is  ready  and  held  carefully,  so  that  the  part  which 
fits  into  the  tube  touches  nothing.  This  is  best  held  by 
an  assistant  during  catheterization,  so  that  it  will  not  be 
contaminated. 

Collection  of  Feces. — The  best  method  of  collecting  feces 
is  to  have  them  passed  directly  into  a  sterilized  Mason  jar. 
This,  however,  is  not  always  practicable,  and  they  may  be 
received  in  a  thoroughly  cleansed  bed-pan  or  chamber  and 
transferred  afterward  to  the  Mason  jar  by  pouring  or  by  a 
pair  of  forceps  sterilized  by  passing  through  a  flame.  The 
cleansing  of  the  receptacle  should  be  done  by  soap  and  water, 
alcohol,  and  sterile  water. 


76 


BACTERIOLOGICAL  EXAMINATION 


Collection  of  Blood  for  Widal  Test. — In  preparing  for  a  Widal 
blood  test  (see  Typhoid  Fever)  the  finger  or  ear  lobe  is 
cleansed  with  soap  and  water  and  alcohol.  It  is  then  pricked 
with  a  needle  and  the  blood  collected  on  unglazed  paper, 
glass  slides,  or  in  glass  tubes.  For  direct  examination  of  the 
blood  the  procedure  with  the  patient  is  the  same. 

Technic  of  Punctures. — Perhaps  the  most  important  bac- 
teriological technic  with  which  the  nurse  has  an  important 
duty  is  the  puncturing  of  cavities  such  as  drawing  fluid 
from  a  chest  or  knee,  the  cerebrospinal  fluid  from  the  spinal 
canal,  or  the  taking  of  blood  from  a  vein.  For  all  these  the 


FIG.  24. — Forms  of  hypodermic  syringe:    A,  Koch's  syringe;  B,  syringe  of 
Strohschein;  C,  Overlack's  form. 

skin  over  the  site  of  operation  is  cleansed  precisely  as  for  a 
major  operation.  It  is  the  practice  of  the  author  for  vein 
puncture,  in  making  a  blood  culture,  to  have  the  arm  at  the 
bend  of  the  elbow  inside  (sometimes  the  leg  is  used)  scrubbed 
with  soap  and  water,  using  a  very  soft  brush,  washed  with 
sterile  water,  and  either  painted  with  10  per  cent,  iodin 
alcohol  or  a  wet  dressing  of  1  per  cent,  formaldehyde  applied; 
if  the  puncture  is  not  done  for  some  time,  fresh  iodin  solution 
is  used  when  everything  is  ready.  These  two  methods  have 
been  found  very  successful  in  destroying  the  bacteria  always 
present  in  the  deeper  layers  of  the  epidermis.  They  are 


MILK  77 

chiefly  small  white  cocci  not  unlike  the  cocci  that  cause 
abscesses.  They  will  be  considered  later  under  the  name 
Staphylococcus  epidermidis  albus. 

There  is  little  to  be  done  by  the  nurse  aside  from  prepara- 
tion and  general  assistance,  but  she  should  know  what  is 
being  done  and  why. 

Fluids  are  removed  from  the  pleural  cavity  or  spinal 
canal  and  elsewhere,  because  in  these  locations  bacteria  of 
specific  kind  or  in  characteristic  conditions  are  to  be  found. 
For  instance,  in  cerebrospinal  meningitis  the  causative 
germs  are  found  within  the  pus  cells  of  the  cerebrospinal 
fluid,  as  double,  biscuit- shaped  cocci,  and  they  have  a  par- 
ticular staining  reaction  by  which  they  are  recognized.  (See 
Chapter  VIII.) 

The  blood  is  taken  from  the  veins  and  grown  in  broth 
alone  or  broth  stiffened  with  gelatin  or  agar-agar  jn  order 
to  find  out  if  living  bacteria  are  circulating  in  the  blood 
stream,  as  is  the  case  in  typhoid  fever  and  septicemia. 

For  entering  these  cavities  or  veins  a  syringe,  preferably 
of  glass,  with  a  good-sized  needle,  larger  than  the  medicinal 
hypodermic  type,  is  used.  The  syringe  and  needle  may  be 
sterilized  by  boiling,  with  a  pinch  of  soda,  for  ten  minutes 
or  by  autoclave,  the  best  means  provided  the  operation  be 
done  immediately.  Metal  parts  will  rust  if  the  syringe  and 
needle  are  sterilized  by  moist  heat  and  allowed  to  dry  out. 
The  hot-air  oven  is  not  suitable  for  sterilizing  in  this  case. 

Milk. — Nurses  are  frequently  required  to  send  samples  of 
milk  for  examination,  especially  in  well-directed  hospitals. 
Of  course,  when  bottled  milk  is  used  an  unopened  quart 
bottle  should  be  sent  to  the  laboratory.  When  the  milk  is 
supplied  in  cans  it  is  necessary  to  have  a  sterilized  50  c.c. 
pipette  and  a  sterilized  bottle  or  flask.  The  lid  of  the  can  is 
carefully  removed,  the  pipette,  held  only  by  the  mouth  end 
and  protected  throughout  its  length  from  touching  the  neck 
of  the  can,  is  plunged  into  the  milk  for  six  inches  and  filled 
by  suction  with  the  mouth.  The  milk  is  transferred  to  the 


78  BACTERIOLOGICAL  EXAMINATION 

sterile  bottle  or  flask,  again  observing  the  precaution  of  not 
touching  the  neck  of  this  container.  The  stopper  or  plug 
of  the  receiving  vessel  is  best  held  by  an  assistant  and  the 
part  which  fits  into  the  vessel  must  touch  nothing.  As  soon 
as  the  milk  is  collected  it  should  be  put  on  ice  or  sent  to  the 
laboratory  immediately. 


CHAPTER  Vril. 

THE  ACUTE  CHIEFLY  LOCALIZED  INFEC- 
TIONS OF  PUS  NATURE— THE 
PATHOGENIC  COCCI. 

So  far  the  general  conditions  under  which  bacteria  live, 
grow,  and  exert  their  peculiar  forces  have  been  considered, 
but  now  a  more  direct  study  will  be  undertaken  of  individual 
groups  and  single  species,  with  the  object  of  learning  what 
the  various  diseases  due  to  microorganisms  are  and  what 
relations  the  germs  bear  to  the  clinical  disease. 

Perhaps  the  most  frequent  condition  a  nurse  has  to  meet 
is  an  abscess  or  local  surgical  infection  with  or  without  pus. 
All  the  technic  of  hospital  work  hinges  on  the  fact  that  organ- 
isms capable  of  producing  pus  are  ubiquitous,  so  that  the 
protection  of  wounds  or  of  patients  of  medical  cases  with 
their  lowered  vital  resistance  is  imperative.  There  is  no  one 
germ  that  always  produces  local  infection  or  pus,  but  many 
bacteria  possess  this  power.  Moreover,  some  bacteria  may 
produce  a  simple  abscess  in  one  case  and  a  violent  inflamma- 
tion of  the  heart  lining  in  another.  This  depends  in  part 
upon  the  virulence  of  the  germ  and  also  upon  its  mode  of 
entry.  If  pus  cocci  fall  upon  a  simple  cut  in  the  skin  of  an 
otherwise  healthy  person  a  red  dropsical  swelling  or  an 
abscess  may  result.  Again,  if  they  fall  upon  a  wound  made 
for  an  abdominal  operation,  they  may  penetrate  to  the  inte- 
rior and  cause  a  peritonitis.  Still,  again,  pus  germs  may 
make  their  entrance  in  the  ways  first  cited,  but  cause  no 
trouble  at  the  site  of  entrance,  being  carried  hence  by  the 
blood  stream  to  cause  trouble  at  other  places.  Any  reaction 
set  up  by  bacteria  is  called  inflammation,  and  in  no  other 

(79) 


80          LOCALIZED  INFECTIONS  OF  PUS  NATURE 
conditions  is  this  so  well  illustrated  as  in  the  effects  of  "pus 


cocci." 


Inflammation. — Inflammation  is  the  reaction  on  the  part 
of  the  body  to  the  presence  of  bacteria  themselves  or  to  their 
products.  It  is  expressed  by  swelling,  increased  heat,  redness, 
pain,  and  some  loss  of  function.  It  is  not  worth  while  to  go 
deeply  into  what  may  be  seen  under  the  microscope  in  inflam- 
mation, but  to  explain  the  physical  expressions  of  inflamma- 
tion just  given  a  few  lines  seems  advisable.  The  swelling, 
heat,  and  redness  are  due  to  an  increase  of  the  blood  in  the 
affected  part,  called  forth  by  forces  exerted  by  the  bacteria. 
These  are  protective  phenomena  whereby  the  body  sends  an 
excess  of  its  most  potent  protective  tissue,  the  blood,  to  stop 
the  onslaught  of  microorganisms.  The  forces  exerted  by 
the  invaders  attract  the  white  cells  of  the  blood,  which  collect 
about  the  outsiders  and  try  to  destroy  them.  The  pain  is 
due  to  the  irritation  of  the  fine  nerves  of  the  part,  and  loss 
of  function  can  be  explained  by  a  combination  of  all  the 
other  features  of  inflammation.  The  further  course  of  this 
reaction  depends  upon  which  force  is  the  stronger,  the  body 
defence  or  the  bacterial  attack.  If  the  former  exceed  the 
latter  the  part  assumes  its  normal  character  after  a  brief 
time.  As  the  infecting  forces  become  greater  in  relation  to 
the  defence,  just  so  there  are  greater  effects  in  the  production 
of  infection,  In  increasing  severity  there  are  the  following 
grades : 

Abscess  is  a  local  collection  of  pus  in  which  the  resistance 
put  up  by  the  tissue  prevents  the  inflammation  from  spread- 
ing, thus  keeping  it  in  a  limited  space.  There  is  some  effect 
on  the  general  body  by  absorption  of  a  few  bacteria  or  their 
poisons,  but  a  densely  packed  zone  of  leukocytes  around  the 
pus  keeps  it  from  general  invasion.  Should  this  barrier  be 
broken  or  the  resistance  be  too  low  to  hold  the  invaders  a 
spread  of  the  pus  occurs  and  cellulitis  or  phlegmon  arises. 
The  next  grade  of  severity  would  be  septicemia  or  pyemia, 
defined  before,  which  arises  when  the  active  inflammation 


INFLAMMATION 


81 


enters  and  involves  the  bloodvessels.  The  softening  of  tissue 
into  pus  is  called  suppuration,  which  may  be  defined  as  the 
destruction  of  tissues  and  cells  by  bacteria  and  their  products. 
Pus  under  the  microscope  is  composed  of  white  blood  cells, 
particularly  the  so-called  polynuclear  leukocytes,  micro- 
organisms, some  of  which  are  free,  others  englobed  by  phago- 
cytes, partly  or  wholly  destroyed  tissue,  and,  at  least  early 


FIG.  25. — Secondary  infection  of  a  glomerulus  of  kidney  by  the  Staphylo- 
coccus  aureus  in  a  case  of  ulcerative  endocarditis.  The  cocci  (stained  doubly) 
are  seen  plugging  the  capillaries  and  also  lying  free.  X  300.  (Muir  and 
Ritchie.) 

in  inflammation,  a  delicate  meshwork  of  coagulum  called 
fibrin;  the  last  is  dissolved  shortly  as  the  suppuration  pro- 
ceeds.  There  is  also  some  turbid  fluid. 

The  fluid  and  cells  which  appear  in   inflammation  are 

collectively  called  an  exudate.    This  may  be  of  several  forms; 

it  may  be  true  pus;  it  may  be  a  thin,  watery  fluid  in  which 

are  floating  shreds  of  a  gray,  friable  character  called  lymph, 

6 


82          LOCALIZED  INFECTIONS  OF  PUS  NATURE 

in  reality  a  coagulum,  such  as  is  formed  in  blood  clotting, 
but  without  red-blood  cells;  it  may  be  a  tenacious  covering 
of  a  surface  called  a  false  membrane,  such  as  is  seen  on  a 
diphtheritic  throat,  more  or  less  closely  adherent  to  the  sur- 
face from  which  it  arises;  it  may  possess  special  characters, 
such  as  hemorrhagic  when  much  blood  is  admixed,  or  mucoid 

when  it  resembles  mucus. 

.  I 

PUS-PRODUCING  MICROORGANISMS. 

It  has  been  stated  that  there  is  no  particular  germ  always 
responsible  for  pus,  but  some  varieties  of  the  round  bacteria 
are  the  commonest  causes.  They  are  called  micrococci  or 
staphylococci  and  streptococci.  Certain  members  of  the 
group  of  cocci  may  also  do  other  things  than  produce  simple 
pus  or  abscesses.  These  will  be  considered  at  the  end  of  this 
chapter.  Bacteria  other  than  cocci  which  can  produce  pus  are 
the  colon  bacillus,  pyocyaneus  bacillus,  and  typhoid  bacillus. 


FIG.  26.— Staphylococcus.      X  1100  diameters.     (Park.) 

Staphylococcus  Pyogenes  Aureus. — Of  the  micrococci  there 
is  one  particular  species  of  importance  which  by  some  bac- 
teriologists has  been  divided  into  two  varieties  because 
members  of  the  group  differ  in  their  ability  to  produce  color 
in  laboratory  cultures  and  because  the  one  having  a  golden- 
yellow  pigment  is  somewhat  more  frequently  found  in  pus. 


PLATE    II 


Cultures  of  Bacteria.     (Besson.) 

The  jellies  upon  which  the  pure  cultures  are  grown,  are 
hardened  in  test-tubes  in  a  slanting  position.  The  bacteria 
are  then  spread  along  the  oblique  surfaces  and  grow  in  bands 
or  streaks  as  shown  here. 


PUS-PRODUCING  MICROORGANISMS  83 

This  color-producing  organism  is  called  the  Staphylococcus 
pyogenes  aureus  (the  golden  pus-producing  coccus).  See 
Plate  II  for  an  idea  of  growth  and  color.  It  is  about  ^^^75-  of 
an  inch  across  and  appears  under  the  microscope  as  single 
individuals,  pairs,  but  more  frequently  in  grape-like  groups. 
It  stains  fairly  well  with  most  dyes  used.  It  does  not  form 
spores  and  does  not  move  from  place  to  place  by  its  own 
power.  It  grows  best  about  85°  F.  It  is  killed  about  56°  C. 
or  130°  F.  at  ten  minutes  in  the  moist  condition,  but  when 
completely  dry  it  may  require  boiling  to  kill.  When  dried 
on  cloth  or  paper  it  may  live  three  months.  This  organism 
grows  well  on  ordinary  laboratory  foodstuffs  and  produces, 
particularly  in  the  presence  of  diffuse  light  and  oxygen,  a 
golden  yellow  color.  This  coccus  has  the  property  of  coagu- 
lating milk  and  liquefying  gelatin  by  the  ferments  it  pro- 
duces. It  is  killed  by  corrosive  sublimate,  1  to  1000,  in  ten 
minutes  in  watery  solution.  In  pus  a  considerably  longer 
time  is  required.  1  to  20  carbolic  kills  in  one  minute;  1  to 
500  in  about  one-half  hour.  The  pus  in  which  the  staphylo- 
coccus  lives  supplies  a  protective  envelope,  and  should  be 
well  mixed  and  diluted  with  the  germicide. 

This  organism  is  very  virulent  for  the  smaller  animals, 
which  may  be  infected  by  rubbing  on  or  injection  under  the 
skin.  It  will  then  produce  a  local  abscess  or  septicemia.  It 
may  produce  acute  inflammation  of  the  interior  of  the  heart, 
or  bone  disease. 

Staphylococcus  Pyogenes  Albus. — The  Staphylococcus  pyo- 
genes albus  is  precisely  like  the  foregoing  except  that  it  does 
not  produce  the  golden-yellow  pigment,  but  grows  in  a  por- 
celain-white manner.  There  is  an  organism  on  the  skin  to 
which  we  give  the  same  name,  but  add  the  word  "epider- 
midis."  It  is  constantly  present  dn  the  surface,  in  the  epider- 
mis, and  in  the  glands  of  the  skin.  Since  its  pus-forming 
ability  is  so  feeble,  "pyogenes"  may  be  omitted  and  the 
name  Staphylococcus  epidermidis  albus  given.  It  does  not 
produce  disease,  but  is  of  constant  annoyance  in  making 


84          LOCALIZED  INFECTIONS  OF  PUS  NATURE 

blood  cultures.  Another  staphylococcus  produces  a  lemon- 
yellow  color. 

These  staphylococci  are  very  widely  distributed  and  seem 
to  be  almost  constantly  upon  the  surfaces  of  the  body,  upon 
skin,  in  the  sebaceous  and  sweat-gland  openings,  on  the 
mucous  membranes.  For  this  reason  they  are  of  great 
surgical  importance  and  may  originate,  in  a  postoperative 
infection,  from  the  patient,  physician,  or  nurse.  Their  rather 
high  resistance  to  disinfection  demands  great  care  in  surgical 
technic.  The  commonest  conditions  in  which  these  cocci 
are  implicated  are  pimples,  boils,  carbuncles,  lymph-gland 
swellings,  osteomyelitis,  and  endocarditis. 

Vaccines  and  Opsonins. — The  use  of  killed  bacteria  to  pro- 
duce an  increased  resistance  against  an  existing  infection 
has  already  been  discussed.  This  method  of  treatment  is 
particularly  suitable  for  infections  with  staphylococci.  The 
procedure  is  about  as  follows:  Cultures  are  made  from  the 
diseased  part,  grown  in  large  quantities  on  laboratory  media, 
washed  off,  suspended  in  physiological  salt  solution  and 
heated  to  a  temperature  which  will  kill  their  disease- 
producing  properties  and  stop  their  multiplication,  but  will 
not  alter  their  peculiar  chemical  composition.  The  number  of 
bacteria  are  then  counted  by  a  special  technic  and  hypodermic 
injections  are  made  of  definite  numbers.  The  size  of  dose  and 
rate  of  increase  of  number  injected  are  controlled  by  what  is 
called  the  opsonic  index.  The  opsonins,  as  will  be  remem- 
bered, are  substances  in  the  blood  which  make  the  bacteria 
suitable  for  ingestion  by  the  white  cells  of  the  blood  or  phago- 
cytes. The  opsonic  index  is  the  relation  of  the  ability  of  the 
patient's  white  cells  to  ingest  bacteria  as  compared  with  a 
normal  person's  white  cells.  This  latter  is  considered  1. 
If  a  person  is  infected  with  the  pus  cocci  it  means  that  his 
opsonic  index  is  below  1,  and  we  try  to  increase  it  up  to  or 
beyond  1.  Many  different  conditions  have  been  found  amen- 
able to  this  treatment,  but  furunculosis  has  responded  better 
than  others. 


PUS-PRODUCING  MICROORGANISMS  85 

Streptococcus  Pyogenes.  —  The  cocci  which  grow  in  chains, 
streptococci,  must  now  be  considered.  There  are  many 
varieties,  but  the  Streptococcus  pyogenes  (the  pus-producing 
streptococcus)  is  the  only  one  that  need  be  considered. 
This  organism  gives  rise  chiefly  to  the  spreading  inflamma- 
tion, such  as  erysipelas,  cellulitis,  and  septicemia.  It  may 
cause  a  localized  abscess.  It  is  a  rapidly  growing  organism 
when  conditions  are  suitable,  and  is  the  commonest  cause 
of  puerperal  infection.  It  frequently  attacks  the  blood  and 
causes  a  solution  of  the  red  cells.  When  streptococci  attack 
serous  membranes,  peritoneum,  pleura,  heart  lining  or 
meninges  the  infection  is  very  severe  and  the  mortality  high. 
It  is  commonly  present  in  the  mouth,  and  may  produce 
tonsillitis.  It  is  not  so  widespread  in  its  distribution  as  the 


FIG.  27.  —  Streptococcus  pyogenes.     (Abbott.) 

foregoing  coccus,  but  is  greatly  feared  in  surgical  and 
maternity  wards.  Streptococci  are  capable  of  producing 
inflammation  of  many  sorts  and  no  tissue  of  the  body  seems 
able  to  resist  them  when  of  sufficient  virulence.  They  most 
commonly  affect  the  tonsil,  heart  lining,  lung,  and  subcu- 
taneous tissue.  Disinfection  of  materials  from  streptococcic 
infections  should  be  done  by  carbolic  acid,  bichloride,  or 
hydrogen  peroxide.  Great  care  is  necessary  in  the  handling 
of  dressings,  clothing,  and  utensils  from  patients  with  strepto- 
coccus infections,  because,  despite  the  low  resistance  of  the 
organism,  transmissions  take  place  quite  easily,  and  it  is 
highly  probable  that  it  always  occurs  by  direct  transference 
of  the  germs  as  they  live  a  very  short  time  exposed  to  light 
and  air.  This  is  particularly  true  of  puerperal  infections, 


86          LOCALIZED  INFECTIONS  OF  PUS  NATURE 

which  are  commonly  the  result  of  infection  with  bacteria 
of  high  virulence.  This  germ,  unlike  the  staphylococcus, 
cannot  infect  through  the  undamaged  skin,  demanding  a 
wound  for  its  entrance.  Streptococci  vary  in  virulence,  and 
when  the  particular  family  of  germs  happens  to  be  very 
virulent  a  single  coccus  may  transmit  an  infection.  The 
streptococcus  is  of  considerable  importance  in  the  production 
of  sore-throat;  it  is  transmitted  from  person  to  person  directly 
or  in  some  manner  that  brings  it  to  the  pharynx,  milk  for 
example.  Septic  sore-throat  usually  appears  in  epidemic 
form  distributed  by  milk  which  has  been  contaminated  by  a 
milkman  having  the  disease  or  from  a  cow  infected  with 
human  streptococci.  Streptococci  in  the  pharynx  seem  to 
be  a  source  of  danger  in  such  conditions  as  scarlatina  and 
measles  because  they  not  uncommonly  are  responsible  for 
complications.  Careful  mouth  hygiene  is  indicated. 

In  diagnosticating  streptococcic  infections  it  is  necessary 
to  make  smears  on  glass  slides  and  cultures  in  appropriate 
media.  The  germs  are  found  to  be  very  small  single  cocci 
varying  from  ^foir  to  2Tirro  of  an  incn>  dividing  only  in 
one  plane  and  therefore  growing  in  chains.  They  are  unable 
to  move  of  themselves,  stain  well  by  most  methods,  multiply 
best  at  37°  C.  (98°  R),  but  also  at  lower  temperatures,  and 
grow  as  very  delicate  gray  colonies.  They  have  no  effect 
upon  milk  or  gelatin.  On  media  containing  blood  they  have 
the  property  of  dissolving  the  red  coloring  matter. 

They  are  killed  in  ten  minutes  when  exposed  to  52°  C. 
(126°  R).  When  dried  in  blood  or  pus  they  may  live  for  a 
considerable  time  at  room  temperature,  but  die  quickly  at 
body  heat  unless  their  food  is  repeatedly  renewed.  They 
are  killed  by  corrosive  sublimate,  1  to  1000;  carbolic  acid, 
1  to  100;  and  hydrogen  peroxide,  1  to  100,  in  ten  minutes  if 
exposed  in  water.  Pus  supplies  a  protective  envelope,  and 
the  germicide  must  be  allowed  to  act  longer.  Streptococci 
are  very  virulent  for  most  lower  animals  and  the  same  lesions 
may  be  produced  by  artificial  injection  as  arise  spontaneously 


MICROCOCCUS  GONORRHEA  87 

in  man.  Streptococci  produce  a  slight  amount  of  extracellular 
poison,  but  more  arises  from  the  disintegration  of  the  bac- 
terial cells.  The  vaccine  treatment  is  not  always  successful. 

An  antistreptococcus  serum  has  been  prepared  by  injecting 
horses  with  a  number  of  cultures  in  order  to  call  forth  anti- 
bodies to  all  varieties.  In  all  cases  of  severe  streptococcus 
infection  this  should  be  used  and  good  results  have  been 
reported  from  some  quarters. 

To  diagnosticate  infections  by  the  staphylococcus  or 
streptococcus  we  are  obliged  to  make  our  technic  suit  the 
individual  case.  If  an  abscess  exist  it  is  sufficient  to  collect 
the  pus.  If  a  cellulitis  or  bone  disease  is  to  be  examined,  it 
is  necessary  to  go  deeply  into  the  tissue  and  select  the  bloody 
material  near  the  healthier  tissue.  In  septicemia  or  heart 
disease  a  blood  culture  is  made.  Both  organisms  grow  with 
ease  upon  ordinary  culture  media. 

MICROCOCCUS  GONORRHEA. 

Gonorrhea  is  an  acute  inflammatory  and  pus-forming 
disease  with  its  chief  manifestations  'in  the  mucous  mem- 
brane of  the  urethra.  It  is  caused  by  the  Micrococcus 
gonorrhea  or  gonococcus,  which  enters  the  mucous  mem- 
brane directly  wherever  there  is  a  slight,  even  invisible, 
abrasion.  This  disease  is  one  of  the  venereal  affections,  and 
is  probably  one  of  the  most  prevalent  of  all  diseases.  In  the 
male  its  acute  stage  lasts  for  three  to  six  weeks,  while  in  the 
female  it  may  be  transient  or  pursue  a  very  long  course.  In 
both  sexes  it  tends  to  infect  the  other  genital  organs,  and  is 
probably  the  chief  cause  of  salpingitis  and  oophoritis.  In 
later  stages  when  all  bacteria  have  not  been  removed  by  a 
perfect  cure,  the  germs  penetrate  to  the  deep  parts  of  the 
mucous  membrane  of  the  external  urinary  channel,  and  there 
rest  for  long  periods  apparently  undestroyed  by  the  protec- 
tive forces  of  the  body,  and  without  setting  up  any  change 
by  which  their  presence  can  be  detected.  They  may  be 


88          LOCALIZED  INFECTIONS  OF  PUS  NATURE 

stimulated  to  renewed  activity  by  a  congestion  of  the  part 
by  any  means.  This  peculiarity  of  hiding  is  the  reason  for 
the  fact  that  a  person  once  affected  by  this  disease  remains 
infective  for  others  for  a  very  long  time.  The  bacteria  reside 
in  the  Bartholin's  glands  of  the  female  or  the  posterior 
urethra,  Cowper's  and  prostatic  glands  of  the  male.  At 
present  there  is  no  perfectly  reliable  method  by  which  to 
ascertain  the  freedom  from  gonococci  of  a  person  once 
affected.  Late  results  of  this  disease  are  urethra!  stricture, 
chronic  inflammation  of  any  other  genitals,  such  as  salpingo- 
oophoritis,  requiring  operative  removal  of  the  affected  parts. 
Either  during  its  acute  or  chronic  stage,  the  latter  more 
commonly,  the  gonococci  may  enter  the  blood  stream  and 
affect  tissues,  other  than  the  genitals,  for  which  it  has  a 
predilection,  the  serous  surfaces,  joints,  heart  lining,  or 
meninges.  These  conditions  arising  after  such  spreading 
are  very  difficult  to  treat  and  not  infrequently  leave  a  per- 
manent defect. 

The  inflammations  of  the  eyes,  notably  the  conjunctiva, 
produced  by  the  gonococcus  are  very  common,  and  one 
authority  says  that  half  the  world's  blindness  is  due  to  it. 
This  complication  is  due  to  carrying  of  germs  from  the  seat 
of  primary  disease,  on  the  fingers,  handkerchiefs  and  the 
like  to  the  eye.  The  result  is  a  frightful  acute,  purulent 
conjunctivitis,  running  a  long,  acute  course  and  leaving 
opacities  of  the  cornea  or  adhesions  of  the  iris  in  many  cases. 
Destruction  of  the  eye  may  result.  Not  only  does  this  dis- 
ease affect  those  with  gonorrhea,  but  it  may  be  transferred 
to  others  by  objects  soiled  with  pus  and  remains  infectious 
so  long  as  there  are  organisms  to  be  found  in  the  exudate. 
The  commonest  transmission  of  gonorrheal  ophthalmia,  as  it 
is  called,  is  to  the  newborn.  This  is  ophthalmia  neonatorum. 
It  is  a  common  practice  of  obstetricians,  especially  in  hos- 
pitals, to  instil  a  few  drops  of  a  weak  nitrate  of  silver  solution 
(2  per  cent.)  into  the  eyes  of  the  newborn,  whether  there 
is  or  is  not  a  history  of  gonorrhea  in  the  mother. 


MICROCOCCUS  GONORRHEA  89 

A  more  serious  and  baffling  phase  of  gonorrhea  is  seen  in 
the  vulvovaginitis  of  little  girls,  which  frequently  sweeps 
like  wildfire  through  a  hospital  ward,  despite  all  attempts  to 
stay  its  progress.  It  also  appears  in  any  institution  where 
children  are  in  close  contact,  schools,  for  example.  It  is 
supposed  to  be  transmitted  by  water-closet  seats  and  directly 
from  child  to  child.  It  may  be  spread  by  bedclothes,  towels, 
clothing,  basins,  bed-pans,  and  in  other  ways.  Children 
have  been  known  to  contract  the  affection  by  occupying  the 
same  bed  as  an  infected  person.  Efforts  to  eradicate  this 
vulvovaginitis  should  be  directed  toward  removing  the  source. 
This  is  sometimes  impossible,  since  it  cannot  always  be  found. 
It  is  much  better  to  institute  a  strict  quarantine  of  every 
little  girl  admitted  to  a  ward  by  using  separate  bed  and  body 
clothing  and  utensils.  She  should  be  examined  by  the  house 
physician  upon  admission,  and  if  necessary,  proper  bacterio- 
logical examinations  made.  If  affected,  such  objects  that 
are  used  on  her  as  can  be  burned  should  be  so  disposed  of. 
Others  should  be  soaked  in  carbolic  acid  solution  for  at  least 
twenty-four  hours.  It  is  the  practice  in  many  places  to  place 
on  all  female  children  a  T-binder,  which  is  burned  upon 
removal.  Patients  must  not  be  allowed  to  go  to  the  water- 
closet,  but  a  bed- pan  used,  to  be  later  disinfected  by  appro- 
priate solutions.  Flaming  objects,  such  as  a  bed-pan,  is  an 
excellent  method  of  disinfection.  The  curious  part  about 
the  transmission  of  vulvovaginitis  is  that  its  causative  agent, 
presumably  always  the  gonococcus,  is  either  in  a  highly 
resistant  state,  or  it  is  protected  in  some  manner,  since 
agencies,  such  as  drying,  that  will  kill  the  bacterium  under 
ordinary  conditions  seem  to  have  little  or  no  effect  upon  it. 

The  gonococcus  was  first  described  by  Neisser  in  1879. 
It  is  classified,  and  correctly,  among  the  round  organisms  or 
cocci,  although  it  is  usually  seen  in  pairs  like  two  kidney  beans 
with  their  concave  sides  together;  they  are  also  said  to  be  of 
biscuit  shape.  Each  bean  is  about  -gimnr  of  an  inch  wide  and 
f  an  mcn  long.  In  pus  or  culture  they  are  of  this 


90 


LOCALIZED  INFECTIONS  OF  PUS  NATURE 


figure,  but  in  the  former  they  are  characteristically  lying 
within  the  pus  cells  between  the  wall  and  the  nucleus,  but 
not  within  the  latter.  Free  pairs  are  also  seen,  but  it  is  unwise 
to  name  them  when  not  in  the  cells,  because  other  cocci  may 
resemble  them.  There  is  a  resemblance  between  these 
organisms  and  those  of  meningitis  (p.  91),  but  the  clinical 
differentiation  is  not  difficult,  since  the  diseases  are  easily 
separated. 

The  gonococcus  does  not  stain  by  Gram's  method,  a  quite 
important  criterion  for  the  bacteriologist.  It  is  cultivated 
with  difficulty.  For  purposes  of  growing  it  in  the  laboratory 


• 


FIG.  28. — Pus  of  gonorrhea,  showing  diplococci  in  the  bodies  of  the  pus  cells. 

(Abbott.) 

a  broth  or  jelly  must  be  used  to  which  has  been  added  some 
blood  or  blood  serum  or  fluid  from  a  hydrocele  or  the  peri- 
toneum. It  grows  best  in  the  presence  of  free  oxygen,  a 
curious  fact,  since  it  will  live  for  long  periods  in  places  where 
there  is  no  free  oxygen.  It  grows  best  at  98°  F.  (37.5°  C.) 
but  dies  out  very  rapidly.  In  the  ice-chest  it  may  live  some- 
what longer. 

Direct  sunlight  kills  the  gonococcus  almost  at  once.  105° 
F.  (41°  C.)  will  kill  the  organism  in  a  few  minutes.  Almost 
any  good  disinfectants  will  kill  it  in  five  minutes  if  directly 
applied  to  the  bare  germ.  "If  completely  dried,  however, 


MICROCOCCUS  INTRACELLULARIS  MENINGITIDIS     91 

and  protected  from  light,  it  may  live  on  sheets  and  clothing, 
from  eighteen  to  twenty-four  hours." 

This  bacterium  produces  an  intracellular  or  endotoxin, 
which  is  as  potent  when  injected  into  animals  as  a  devitalized 
mass  as  the  living  form  itself,  although  the  gonococcus  has 
very  little  effect  upon  laboratory  experimental  animals. 
Some  observers  have  been  able,  by  injecting  goats  with  coccus 
poison  or  the  germs  themselves,  to  produce  an  antiserum 
against  the  gonococcus,  and  therewith  treat  human  cases 
with  some  success.  Vaccination  with  killed  gonococci  has 
been  found  of  some  value  in  chronic  stages,  and  by  some 
observers,  in  acute  stages  also. 

The  bacteriological  diagnosis  is  easily  made  by  spreading 
some  of  the  pus  upon  glass  slides,  staining  appropriately,  and 
examining  under  the  microscope.  In  the  chronic  gonococcus 
infection  the  discovery  of  the  germ  is  extremely  difficult. 
For  the  diagnosis  of  obscure  cases  of  vulvovaginitis  Dr. 
Norris  recommends  a  washing  with  1  to  5000  bichloride 
solution  in  a  pipette  filled  with  a  bulb.  The  chemical 
removes  the  surface  epithelium  and  cocci  hidden  in  the  depths 
are  drawn  out.  The  fluid  can  be  centrifugalized  and  the 
sediment  stained. 


MICROCOCCUS  INTRACELLULARIS  MENINGITIDIS. 

Meningitis,  or  inflammation  of  the  membranes  covering 
the  brain  and  spinal  cord,  may  be  caused  by  several  bacteria, 
such  as  streptococci,  pneumococci,  and  influenza  bacilli, 
but  we  shall  deal  chiefly  with  epidemic  cerebrospinal  menin- 
gitis or  spotted  fever.  (The  latter  is  a  common  term  which 
should  be  discarded  for  meningitis  and  confined  to  typhus 
or  jail  fever.)  Epidemic  cerebrospinal  meningitis  is  an  acute 
primary  inflammation  due  to  a  coccus  called  the  Micrococcus 
or  Diplococcus  intracellularis  meningitidis  of  Weichselbaum 
or  the  meningitis  coccus  or  meningococcus.  The  organism 
probably  gains  access  to  the  meninges  by  way  of  the  nose, 


92          LOCALIZED  INFECTIONS  OF  PUS  NATURE 

whence  it  passes  through  the  sieve-like  bones  through  which 
the  olfactory  nerves  emerge  from  the  skull.  By  this  route 
it  penetrates  to  the  under  surface  of  the  brain  and  extends 
along  the  meninges.  It  can,  however,  invade  the  blood 
stream  first  and  later  cause  lesions  of  meningitis. 

The  other  agents  of  meningitis,  the  pneumococcus  for 
instance,  usually  gain  entrance  by  way  of  the  blood  or  lymph, 
directly  through  the  skull-base  or  by  an  extension  from  the 
middle  ear,  where  suppuration  may  burrow  through  the 
bone. 

The  meningitis  coccus  is  found  in  the  nose  and  throat  of 
patients,  in  the  nose  and  throat  of  about  10  per  cent,  of  their 
attendants,  and  in  a  varying  percentage  of  persons  with 
whom  the  cases  come  in  contact.  The  last  are  called  carriers 
and  are  of  considerable  importance  in  epidemics  because, 
not  being  ill  with  the  disease,  they  move  about  exposing 
others  when  they  cough  or  sneeze.  It  is  the  practice  in  epi- 
demic times  or  in  camps  to  make  cultures  from  the  nose  and 
throat  of  persons  exposed  to  meningitis  for  the  detection  of 
carriers,  who  are  then  segregated  and  treated  by  some  anti- 
septic like  Dakin's  solution;  only  when  upon  reculture  they 
are  found  free  of  the  meningitis  coccus  are  they  allowed  to 
go  about  their  usual  business. 

The  affection  produces  a  thick,  stringy,  purulent  exudate 
in  the  spaces  between  the  nervous  system  and  their  coverings, 
the  meninges,  called  the  arachnoid  space.  This  exudate 
covers  the  brain  and  cord  and  fluid  accompanying  it  dis- 
tends the  various  cavities  of  the  spinal  column  and  interior 
of  the  brain.  The  disease  has  a  high  mortality.  It  is  much 
more  common  among  children  and  young  people  than  in 
those  over  thirty  years  of  age.  Its  results  or  sequels  consist 
in  blindness,  deafness,  and  paralyses  of  various  kinds.  Men- 
tality may  be  affected. 

In  taking  care  of  meningitis  patients  the  chief  concern  is 
with  discharges  from  the  nose  and  mouth.  These  cavities 
should  be  cleansed  with  a  mild  antiseptic,  say  boric  acid, 


MICROCOCCUS  INTRACELLULARIS  MENINGITIDIS      93 

and  the  cotton  or  what  not  used  should  be  burned  or  soaked 
in  carbolic  acid  solution.  The  nose  and  throat  of  those  in 
attendance  should  be  sprayed  with  an  antiseptic,  those  con- 
taining thymol  being  excellent  for  the  purpose.  It  is  also 
well  for  attendants  and  necessary  visitors  to  wear  gauze 
masks.  After  death  the  body  should  be  encased  in  a  cloth 
wetted  with  carbolic  acid  solution. 


FIG.  29. — Meningococcus  in  spinal  fluid.    (Hiss  and  Zinsser.) 

In  the  diagnosis  of  this  disease  from  a  bacteriological 
stand-point  the  most  important  procedure  is  the  lumbar 
puncture.  This  is  the  introduction  of  a  needle  into  the 
meningeal  space  by  entering  between  the  vertebrae  of  the 
lumbar  region.  Its  purpose  is  the  withdrawal  of  fluid.  This 
fluid  is  usually  thin,  turbid  pus  containing  flakes  of  fibrin. 


94          LOCALIZED  INFECTIONS  OF  PUS  NATURE 

The  turbidity  is  due  to  great  numbers  of  pus  cells.  These 
cells  contain  the  cocci  of  meningitis,  which  are  of  the  same 
general  size,  shape,  and  arrangement  as  the  gonococcus. 
They  are  so  like  this  coccus  that  one  must  be  well  versed 
indeed  to  differentiate  between  the  two  without  a  knowledge 
of  the  source  of  the  specimen.  The  meningitis  cocci  show  a 
great  variance  in  size  and  shape  within  the  same  specimen, 
conditions  not  common  with  the  gonococci.  They  also 
stain  differently,  although  both  are  decolorized  in  the  Gram 
method.  As  is  the  case  with  gonococcus  they  lie  within  the 
protoplasm,  but  not  in  the  nucleus.  Given  a  turbid  fluid 
from  a  case  suggestive  of  meningitis,  it  is  possible  to  make  a 
diagnosis  by  finding  these  cocci  because  gonococci  practically 
never  cause  meningitis.  The  cocci  may  also  be  found  in  the 
bleod.  They  develop  agglutinins  whereby  an  additional 
assistance  in  diagnosis  may  be  given. 

The  cocci  are  grown  with  moderate  ease  on  laboratory 
media,  especially  if  they  contain  blood  serum  or  glucose. 
They  grow  best  in  the  presence  of  oxygen  at  37.5°  C.  or 
98°  F.,  but  die  rapidly  if  not  put  on  fresh  food  frequently. 

They  are  killed  by  heating  to  50°  C.  or  122°  F.  for  ten 
minutes,  by  exposure  to  sunlight  at  once,  and  by  almost  all 
disinfectants  in  appropriate  strength  in  five  minutes. 

It  has  been  possible  to  produce  a  very  effective  antiserum 
by  injecting  into  horses  suspensions  of  whole  and  disinte- 
grated meningitis  cocci.  The  antiserum  is  introduced  into 
the  space  between  the  cord  and  the  meninges  by  lumbar 
puncture,  first  withdrawing  some  of  the  spinal  fluid  to  make 
room  for  it.  By  this  treatment,  especially  when  instituted 
early  in  the  disease,  a  great  deduction  in  the  mortality,  and 
in  the  deformities  so  frequently  following  meningitis,  has 
been  effected.  Since  certain  cases  exhibit  septicemic  char- 
acters, the  serum  should,  under  such  circumstances,  also  be 
given  into  the  blood  stream. 


DIPLOCOCCUS  PNEUMONIA  95 


DIPLOCOCCUS  (STREPTOCOCCUS)  PNEUMONlffi. 

Pneumonia  or  inflammation  of  the  lungs  may  be  caused 
by  a  great  many  organisms,  but  by  far  the  commonest  one 
is  the  Diplococcus  or  Streptococcus  pneumonic?  or  pneumo- 
coccus.  This  omnipresent  organism  gains  entrance  to  the 
body  almost  exclusively  by  the  nose  or  mouth.  It  enters 
the  air  passages  and  penetrates  to  the  finer  parts  of  the  lungs, 
there  setting  up  a  rather  characteristic  inflammation.  In 
certain  types  of  pneumonia  the  disease  may  involve  whole 
lobes;  again,  small  patches  here  and  there  may  be  involved, 
the  intervening  tissue  being  practically  normal.  From  the 
lungs  the  bacteria  naturally  penetrate  into  the  blood  stream. 
This  emphasizes  the  fact  that  while  pneumonia  expresses 
itself  chiefly  in  the  lungs,  it  is  in  reality  a  general  infection. 
It  should,  moreover,  be  included  among  the  transmissible 
infections  because  it  appears  in  epidemics,  and  definite 
instances  of  communication  directly  from  the  sick  to  the 
well  are  known. 

By  reason  of  the  spread  of  pneumococci  through  the  blood, 
complications  in  the  form  of  involvement  of  nearly  every 
tissue  in  the  body  may  result.  The  interior  of  the  heart,  the 
pleura,  and  the  meninges  are  most  commonly  affected.  These 
organisms  may  also  cause  conjunctivitis,  tonsillitis,  otitis, 
and  arthritis. 

For  diagnosis  bacteriologically,  cultures  are  made  from 
the  sputum,  selecting  the  blood-streaked  specimens,  and  of 
the  blood.  Read  pages  73  to  75  for  collection  of  sputum 
for  bacteriological  purposes.  Sputum  should  be  disinfected 
by  receiving  it  directly  in  5  per  cent,  carbolic  solution.  Not 
only  must  care  be  used  to  collect  sputum,  but  the  lips  and 
cheeks  of  the  patient  should  be  kept  clean,  and  all  attend- 
ants should  rinse  their  nose  and  throat  frequently  with 
hydrogen  peroxide  or  Dobell's  solution.  Pneumococci  do 
not  live  long  on  objects,  but  may  be  transferred  by  persons 
in  the  hair  and  nasopharynx,  in  which  places  the  germs  are 


96 


LOCALIZED  INFECTIONS  OF  PUS  NATURE 


protected  from  light  and  drying.  After  pneumonia  it  is  not 
common  for  patients  to  remain  as  carriers,  but  attendants 
may  be  accidental  carriers. 


FIG.  30. — Pneumococcus  from  bouillon  culture,  resembling 
streptococcus.     (Park.) 


FIG.  31. — Pneumococci  in  peritoneal  pus.     Stained  with  fuchsin.      X  1000 
diameters.     Clear  spaces  indicate  capsules.     (Park.) 


The  coccus  belongs  properly  to  the  streptococci,  since  it 
divides  only  in  one  plane,  and  its  cultures  may  appear  in 
chains.  It  has  the  peculiarities  of  growing  in  an  oval  shape 


PLATE   III 


Diploeoccus  Pneumonias  in   Blood  of  Rabbit.      (Abbott.) 

Showing  encapsulated   cocci,  reel  arid  w^ite  blood  cells. 


DIPLOCOCCUS  PNEUMONIA  97 

in  pairs,  with  the  distal  ends  pointed  (lance-shape),  and 
being  surrounded  by  a  capsule.  This  shape  and  envelope 
are  quite  characteristic,  and  almost  determinative.  The 
coccus  grows  very  slightly  on  ordinary  culture  media,  but 
best  when  blood  or  blood-coloring  matter  is  added.  It  then 
produces  a  faint  green  color  and  grows  best  at  37°  C.  or  98°  F., 
but  does  not  live  long,  requiring  repeated  transference  to 
fresh  food.  In  sputum  the  pneumococcus  may  remain  alive 
and  capable  of  producing  disease  for  several  months  if  pro- 
tected from  light.  If  the  sputum  be  dried  and  powdered, 
so  that  it  could  be  inhaled,  the  cocci  live  for  a  few  days  in 
diffused  light.  Direct  sunlight  kills  them  almost  immediately. 
They  are  killed  at  52°  C.  or  126°  F.  in  ten  minutes.  It  is 
said  that  the  best  way  to  disinfect  sputum  is  by  the  addition 
of  about  one-third  alcohol.  The  pneumococcus  itself  has  a 
very  low  resistance  to  any  of  the  ordinary  disinfectants, 
being  killed  in  a  few  minutes. 

Most  of  the  lower  animals,  particularly  mice  and  rabbits, 
but  not  birds,  are  susceptible  to  the  pneumococcus.  How- 
ever, a  true  pneumonia  as  seen  in  man  has  not  been  produced 
artificially.  The  pneumococcus  produces  a  small  quantity 
of  poison  aside  from  itself,  but  acts  chiefly  by  reason  of  sub- 
stances within  the  germ  cell.  It  has  been  found  that  there  are 
four  closely  related  varieties  of  pneumococci  capable  of  caus- 
ing pneumonia  and  that  against  one  of  them  it  is  possible 
to  produce  in  horses  a  powerful  antiserum.  In  a  given  case 
of  pneumonia  the  causative  strain  of  cocci  is  isolated  and 
studied;  if  it  belongs  to  the  type  for  which  the  antiserum  is 
available  this  may  be  injected  under  the  skin  or  into  a  vein. 
The  death-rate  of  pneumonia  for  this  one  type  has  been 
somewhat  reduced  by  the  serum  treatment.  The  use  of 
vaccines  therapeutically  has  not  been  followed  by  uniformly 
favorable  results,  but  prophylaxis  by  this  means  seems  to 
hold  out  some  promise.  The  blood  in  pneumonia  contains 
some  agglutinins,  but  they  are  not  of  much  value  in  diag- 
nosis. 
7 


CHAPTER  IX. 
THE  ACUTE  SELF-LIMITED  INFECTIONS. 

IN  this  chapter  are  included  the  infectious  diseases  which 
are  due  to  a  specific  microorganism  and  which  tend  to  run  a 
definite  course. 

BACTERIUM  DIPHTHERLffi. 

Diphtheria  is  a  disease  caused  by  the  Bacterium  diphtheric?, 
or  diphtheria  bacillus,  or  Klebs-Loffler  bacillus,  characterized 
by  the  development  of  a  so-called  false  membrane  upon  a 
mucous  membrane  or  abraded  surface,  from  which  the  soluble 
poisons  are  absorbed  by  the  circulation.  This  false  mem- 
brane is  an  inflammatory  exudate  thrown  out  by  the  body 
under  the  stimulus  of  the  bacteria  as  a  means  of  protection 
against  them.  Myriads  of  bacteria  are  included  in  the 
meshes  of  this  exudate.  If  the  false  membrane  be  removed  a 
raw,  bleeding  surface  is  exposed.  Sometimes  this  is  done  for 
the  purpose  of  applying  remedial  agents.  The  false  mem- 
brane of  diphtheria  appears  most  commonly  upon  the  throat 
and  nose,  but  it  may  be  found  upon  the  eye,  vagina,  or  skin 
wound. 

This  is  the  disease  par  excellence  for  explaining  the  effect 
of  toxins  extracellular  and  separable  from  the  bacteria.  The 
organisms  do  not  enter  the  body  but  only  their  toxins  are 
absorbed,  and  are  responsible  for  the  clinical  symptoms  of 
the  illness,  such  as  moderate  fever  with  rapid  pulse  and 
great  prostration.  They  are  also  responsible  for  the  paralyses 
which  frequently  follow  an  attack,  such  as  heart  weakness 
or  laryngeal  failure. 
(98) 


BACTERIUM  DIPHTHERIA  99 

Diphtheria  is  contracted  by  receiving,  on  a  susceptible 
surface,  some  of  the  bacteria  themselves.  They  usually 
come  from  an  active  case.  However,  after  recovery  from  the 
attack,  at  a  time  when  no  symptoms  exist,  fully  virulent 
bacteria  may  remain  in  the  throat  for  many  days.  People 
with  such  a  condition  are  called  ''carriers,"  and  strict 
hygienic  measures  are  being  taken  now  by  all  health  authori- 
ties to  prevent  spread  of  the  disease  by  such  means.  Cough- 
ing or  sneezing  dislodges  particles  containing  diphtheria 
bacilli  and  spread  the  disease.  Infection  has  been  known 
to  travel  by  milk,  where  the  dairyman  had  a  case  on  his 
farm.  The  milk  had  become  infected  by  those  handling  it. 
Nurses  and  doctors  contract  the  disease  frequently  by  their 
close  association  with  the  patient.  They  can  protect  them- 
selves while  inspecting  a  throat  by  placing  a  piece  of  glass 
before  the  patient's  mouth,  so  that  if  he  cough  the  organisms 
will  not  get  into  the  examiner's  face.  The  absolute  isolation 
of  patient  and  nurse  is  now  demanded  by  health  authorities. 
A  case  of  diphtheria  remains  infectious  while  there  are 
virulent  bacilli  on  the  inflamed  surface;  in  the  throat  this  is 
nearly  always  two  weeks  or  longer.  Isolation  and  disinfec- 
tion must  therefore  be  kept  up  for  this  period  at  least  and 
when  possible  until  two  cultures  twenty-four  hours  apart 
fail  to  show  the  presence  of  organisms. 

All  materials  that  can  be  so  treated  should  be  burned. 
Utensils  and  fabrics  should  be  soaked  in  carbolic  acid  solu- 
tion and  then  boiled.  Great  care  must  be  used  by  the  nurse 
with  her  hands,  face,  nose,  throat,  hair,  and  clothes.  The 
lodgment  of  diphtheria  bacilli  in  the  hair  is  of  special  danger, 
since  they  remain  active  for  a  long  time.  To  prevent  the 
settling  of  the  bacilli  in  the  hair  it  is  advisable  to  wear  a  cap 
that  will  completely  cover  the  head.  Thorough  washing 
with  soap  and  water  and  drying  in  the  sun  are  advisable 
when  the  nurse  leaves  the  patient.  Since  the  bacilli  spread 
through  the  air,  sheets  wetted  with  disinfectants  should  be 
hung  about,  particularly  at  doors. 


100        THE  ACUTE    SELF-LIMITED    INFECTIONS 

For  diagnosis  of  diphtheria  use  is  made  of  direct  examina- 
tion of  stained  smears  from  the  site  of  trouble,  and  cultures 
upon  blood  serum,  the  best  culture  medium. 

The  bacilli  are  rather  characteristic  in  their  irregular  shape. 
They  are  rods  of  unequal  length  and  width,  full  of  granules, 
which  stain  more  deeply  than  the  rest  of  the  rod.  Their 
ends  are  usually  clubbed  or  the  whole  rod  may  have  the 
shape  of  a  wedge.  They  may  be  straight  or  bent.  They  vary 


A. 


FIG.  32. — Bacterium  diphtherias:  A,  its  morphology  on  glycerin-agar- 
agar;  R,  its  morphology  on  Loffler's  blood  serum;  C,  its  morphology  on  acid- 
blood  serum  mixture.  (Abbott.) 

from  :TOTO  "o  to  21^07  of  an  inch  in  length  and  from  STFWIF  to 
2T  i"0"o  °f  an  inch  in  breadth.  They  are  very  apt  to  show  pecu- 
liar, more  or  less  characteristic  forms  of  degeneration.  A 
special  stain  called  Loffler's  alkaline  methylene-blue  solution 
is  used  to  show  the  peculiarities  of  their  structure.  The 
diphtheria  bacilli  are  non-motile,  non- spore-bearing  rods. 
They  are  not  pronounced  in  their  manifestations  of  life  under 
artificial  conditions,  except  for  toxin  production,  but  they 


BACTERIUM  DIPHTHERIA  101 

grow  readily  on  most  laboratory  culture  media.  Solidified 
blood  serum  is  the  preferred  artificial  foodstuff.  Upon  it 
they  grow  in  such  a  manner  as  to  render  diagnosis  easy,  both 
by  the  naked-eye  appearance  and  by  their  shapes  under  the 
microscope.  These  bacilli  grow  best  at  the  body  temperature, 
37°  C.  or  98°  F.,  but  also  at  a  lower  point. 

They  are  killed  at  58°  C.  or  140°  F.  for  ten  minutes.  Boil- 
ing kills  in  one  minute.  In  the  dry  state,  protected  from 
daylight,  these  organisms  may  live  several  months.  With 
such  protection,  when  moist  or  in  exudate,  as  from  the  throat, 
life  may  persist  for  at  least  four  months.  Direct  sunlight 
kills  within  half  an  hour.  On  cloth  or  other  absorbing 
material  their  life  is  long,  but  indeterminate.  On  coins  they 
die  in  twelve  to  thirty-six  hours.  On  toys,  lead-  and  slate- 
pencils  and  tumblers  they  may  live  several  weeks.  They 
do  not  live  long  in  cultures  unless  frequently  transferred  to 
fresh  food.  They  resist  cold.  These  data  concerning  the 
viability  of  the  Klebs-LofBer  bacillus  in  the  outer  world  help 
to  explain  the  sudden  and  otherwise  inexplicable  outbreaks 
of  diphtheria,  and  the  difficulties  of  their  eradication.  To 
disinfectants  they  present  a  slightly  greater  resistance  than 
most  non-spore-bearing  bacilli.  Carbolic  acid,  1  to  100, 
kills  in  ten  minutes;  corrosive  sublimate,  1  to  1000,  in  twenty 
minutes.  Hydrogen  peroxide  kills  them  rather  easily. 
These  figures  are  for  bacteria  suspended  in  water. 

Diphtheria  bacilli  will  kill  most  experimental  animals, 
but  the  guinea-pig  is  the  most  susceptible.  Here  they 
characteristically  produce  a  sloughing  at  the  site  of  inocula- 
tion, a  peritonitis,  and  a  congestion  of  the  adrenal  gland. 
Sometimes  organisms  suggestive  of  diphtheria  bacilli  are 
found  in  the  throat  without  a  membrane.  In  order  to  prove 
if  these  be  true  diphtheria  forms,  some  of  a  culture  is  injected 
under  the  skin  of  a  guinea-pig.  If  the  changes  described  are 
produced,  and  the  animal  dies  in  three  days,  it  shows  that 
the  organism  in  question  was  a  true  virulent  diphtheria 
bacillus. 


102        THE    ACUTE    SELF-LIMITED    INFECTIONS 

Diphtheria  Antitoxin. — The  specific  poison  of  the  organisms 
and  the  means  used  to  neutralize  it  must  now  be  discussed. 
The  poison  of  the  diphtheria  bacillus  is  not  only  made  in 
the  false  membrane  in  the  human  case,  but  is  elaborated  by 
the  organism  in  artificial  media  in  a  laboratory.  This  poison 
itself  will  kill  the  lower  animals.  The  toxin  is  obtained  by 
growing  the  germs  on  broth,  made  in  a  manner  found  most 
suitable  for  its  development.  The  broth  is  freed  of  bacterial 
bodies  and  injected  into  horses.  This  animal  is  chosen  for 
its  size  and  freedom  from  disease  affecting  humans,  and 
because  large  quantities  of  material  may  be  injected  and 
much  blood  withdrawn  without  harming  the  beast.  The 
horses  receive  under  the  skin  gradually  increasing  amounts 
of  this  toxic  broth  until  they  are  able  to  withstand  huge 
quantities,  many  times  the  dose  necessary  to  kill  them  if 
given  at  first.  They  are  then  considered  to  have  some  neu- 
tralizing substances  for  this  toxin.  This  neutralizing  property 
is  known  to  be  in  the  blood  serum.  The  horse  is  then  bled, 
and  the  serum  separated  from  the  red  blood  cells.  It  is 
tested  against  the  original  toxin  used  for  making  the  injec- 
tions. This  is  done  by  mixing  the  two  in  definite  parts, 
allowing  the  mixture  to  stand  a  few  minutes,  and  injecting 
it  into  guinea-pigs.  By  appropriate  technic  the  number  of 
"units"  is  determined.  A  "unit"  is  that  quantity  of  horse 
serum,  or  antitoxin,  which  will  neutralize  100  times  the 
smallest  quantity  of  toxin  necessary  to  kill  a  guinea-pig 
weighing  250  grams  (8  ounces) . 

The  horse-serum  antitoxin  has  now  a  value  for  clinical 
purposes,  as  the  quantity  to  be  given  can  be  controlled. 
Newer  methods  have  permitted  the  refinement  and  concen- 
tration of  this  antitoxin,  so  that  there  is  now  less  incon- 
venience in  giving  it.  The  dose  for  treatment  varies  from 
1500  to  20,000  units  by  injection  under  the  skin  depending 
upon  the  severity  of  the  case;  in  bulk  this  may  be  less  than  a 
teaspoonful.  In  very  severe  or  malignant  diphtheria  the 
best  results  are  obtained  by  giving  the  antitoxin  into  a  vein. 


BACTERIUM  DIPHTHERIA  103 

For  immunizing  purposes,  that  is,  to  protect  persons  exposed 
but  not  yet  suffering  from  the  disease,  from  300  to  1000  units 
are  used.  In  both  cases  a  repetition  of  the  dose  is  frequently 
demanded,  and  in  case  the  exudate  does  not  fade,  the  injec- 
tions may  have  to  be  given  several  times.  The  effect  is  a 
passive  acquired  immunity,  as  it  is  the  addition  of  a  toxin- 
neutralizing  substance  to  aid  tissues,  for  which  they  them- 
selves have  not  worked.  The  visible  effects  of  antitoxin 
administrations  are  a  rather  rapid  disappearance  of  the  false 
membrane,  a  fall  of  temperature,  and  a  lessening  of  consti- 
tutional prostration. 

For  the  best  results  in  the  treatment  of  diphtheria,  anti- 
toxin should  be  used  early.  Each  hour  of  delay  in  using  it 
after  the  diagnosis  has  been  made  reduces  the  good  changes 
of  the  patient.  For  large  cities  the  decrease  in  mortality 
has  been  50  per  cent.,  and  in  the  favorable  cases,  even  75 
per  cent. 

As  is  well  known  not  all  persons  are  susceptible  to  diph- 
theria, indeed  a  rather  small  percentage  do  contract  the  dis- 
ease. This  is  due  to  the  fact  that  the  blood  serum  of  unsus- 
ceptible individuals  contains  natural  antitoxin,  so  that  viru- 
lent bacilli  alighting  on  the  throat  find  an  unfavorable  place 
to  grow.  Advantage  has  been  taken  of  this  condition  in  the 
Schick  test  which  consists  of  the  introduction  of  a  minute 
amount  of  diphtheria  toxin  into  the  layers  of  the  skin.  If  the 
person  be  susceptible  to  diphtheria,  that  is,  has  no  natural 
antitoxin,  a  red  swollen  area  will  appear  in  twenty-four  to 
forty-eight  hours.  If,  on  the  other  hand,  antitoxin  is  present 
no  reaction  occurs  because  the  small  amount  of  toxin  put 
into  the  skin  has  been  neutralized;  such  an  individual  is 
rather  certain  not  to  contract  diphtheria  and  does  not  require 
the  immunizing  dose  of  antitoxin  if  exposed.  About  80  per 
cent,  of  infants  and  adults  give  a  negative  reaction;  children 
and  adolescents  give  a  lower  percentage,  showing  what  is 
borne  out  by  clinical  observation,  that  they  are  more  sus- 
ceptible to  the  disease.  This  test  saves  much  time  and 


104        THE    ACUTE    SELF-LIMITED    INFECTIONS 

trouble  in  quarantine  and  reduces  very  greatly  the  number 
of  individuals  who  must  receive  an  immunizing  dose  when 
exposed  to  a  case.  It  has  been  found  possible  also  to  immunize 
Shick  positive  individuals  by  injecting  mixtures  of  antitoxin 
and  toxin,  the  two  being  combined  in  such  a  manner  that 
the  toxin  is  not  at  all  dangerous.  This  procedure  is  espe- 
cially valuable  for  nurses,  doctors,  and  attendants  in  hos- 
pitals or  wards  devoted  to  this  disease. 

Pseudodiphtheria  Bacilli. — There  is  a  group  of  organisms 
called  pseudodiphtheria  bacilli,  because  of  their  resemblance 
in  morphology  and  growth  to  the  true  disease-producing 
type.  They  are  sometimes  found  in  jaw  abscesses  or  otitis 
media.  They  do  not  produce  the  t  pical  diphtheritic  sore- 
throat.  The  presence  of  such  forms  in  the  throat  often  leads 
to  erroneous  diagnoses  and  lengthens  quarantine.  Quar- 
antine is  demanded  by  health  authorities  until  the  throat  is 
shown  to  be  clear  of  diphtheria  bacilli. 

BACILLUS  TETANI. 

Tetanus  or  lockjaw  is  a  disease  characterized  by  tonic 
and  clonic  spasms  of  the  muscles  due  to  the  effect  of  the 
soluble  poisons  of  the  Bacillus  tetani  or  tetanus  bacillus  upon 
the  central  nervous  system.  This  poison,  like  that  of  the 
diphtheria  germ,  is  separable  or  extracellular.  It  is  produced 
by  the  bacteria,  absorbed  along  the  motor  nerves,  and 
carried  to  the  brain  and  cord.  Tetanus  bacilli  enter  the  body 
almost  invariably  by  punctured  or  lacerated  wounds.  They 
multiply  in  the  deep,  covered  position  afforded  by  such 
wounds,  but  are  not  themselves  taken  up  by  the  blood  to  be 
distributed  throughout  the  body,  only  their  poisons  being 
absorbed.  The  bacteria  are  common  in  soil,  manure,  dust 
from  covered  places,  wood  and  the  like.  Their  vitality  is 
considerable,  due  to  the  formation  of  resistant  spores. 

Wounds  carry  the  germs  beneath  the  skin,  where  they  lie 
covered  and  hidden  in  the  deeper  tissues.  They  do  not  grow 


BACILLUS  TETANI  105 

in  the  presence  of  oxygen  (anaerobic),  so  that  a  secluded 
place  in  the  depths  of  wounds  favors  their  development  and 
that  of  their  toxin.  Simple  uncomplicated,  open  wounds 
are  probably  never  the  site  of  development  for  tetanus 
bacilli.  If  other  germs  are  introduced  the  tissues  are  further 
devitalized  by  them,  and  they  absorb  any  available  free 
oxygen,  so  that  favorable  conditions  for  tetanus  are  increased. 
Either  spores  or  vegetating  germs  may  be  introduced  on 
rusty  nails,  splinters  of  wood  or  glass,  blank- cartridge  plugs, 
the  grinding  of  dirt  into  wounds  or  by  introduction  of  dirt 
or  soiled  clothing  in  shell  wounds.  Tetanus  sometimes 
appears  in  the  newborn  or  in  the  puerperal  mother,  particu- 
larly after  instrumental  delivery.  Ordinary  gelatin,  some- 
times injected  under  the  skin  to  arrest  hemorrhage,  is  said 
to  often  contain  spores. 

Between  the  time  of  introduction  of  the  germs  and  the 
outbreak  of  symptoms  a  period  of  incubation  elapses  which 
may  be  as  short  as  three  days  or  as  long  as  six  weeks.  The 
muscles  nearest  the  wound  are  affected  first,  as  a  rule,  but 
the  characteristic  symptoms  of  lockjaw  soon  appear.  After 
death  very  little  is  to  be  found  by  postmortem. 

The  danger  from  patients  with  tetanus  is  quite  inconsider- 
able, the  only  infective  material  being  the  discharges  from 
the  wound  or  the  pieces  cut  away  surgically.  Such  objects 
are  used  for  injection  into  animals  to  establish  a  diagnosis. 
This,  however,  is  seldom  necessary,  as  tetanus  is  quite  clear 
in  its  symptomatology.  All  dressings  and  pieces  removed 
surgically  must  be  burned  with  actual  fire.  Boiling  and 
baking  are  unreliable.  The  first  treatment  usually  under- 
taken is  the  surgical  cutting  away  of  skin  and  subcutaneous 
tissue  far  beyond  the  original  wound,  in  order  to  remove  all 
bacilli.  If  these  are  removed  no  more  toxin  can  be  made. 

The  tetanus  bacillus  is  large,  faToU  to  ^oVo  mcn  l°ng  DV 
50000  to  30000  inch  wide;  it  is  a  motile,  spore-bearing 
bacillus,  growing  only  when  the  atmospheric  oxygen  is  shut 
out.  The  motility  is  due  to  flagella  arranged  all  about  the 


106        THE    ACUTE    SELF-LIMITED    INFECTIONS 

cell  wall.  The  spores  develop  at  one  end  and  give  the  rod 
a  drumstick  appearance;  they  are  best  seen  in  old  cultures. 
The  spores  may  leave  the  parent  bacillus  and  lead  an  inde- 
pendent existence.  In  this  state  they  are  not  motile  and  are 
stained  with  great  difficulty.  The  vegetative  rod,  however, 
stains  with  comparative  ease.  The  organism  can  digest 
gelatin  and  grows  characteristically  in  it. 

In  discussing  the  resistance  of  this  germ  to  deleterious 
agents,  the  spores  only  need  be  considered,  because  the 
vegetative  rod  has  the  power  of  going  into  this  resistant 
stage  very  quickly  when  it  meets  unfavorable  environment. 


9: 


FIG.  33. — Tetanus  bacilli  with  spores  in  distended  ends.      X  1 100  diameters. 

•  (Park.) 

The  rods  grow  best  at  37°  C.  or  98°  F.  The  spores  are  killed 
at  105°  C.,  221°  F.,  when  exposed  ten  minutes  to  streaming 
stream.  They  are  destroyed  by  chemicals  as  follows:  5 
per  cent,  carbolic  acid  in  ten  hours;  5  per  cent,  carbolic  acid 
plus  0.5  per  cent,  hydrochloric  acid  in  two  hours;  1  to  1000 
corrosive  sublimate  in  three  hours;  1  to  1000  corrosive  sub- 
limate plus  0.5  per  cent,  hydrochloric  acid  in  one-half  hour; 
1  per  cent,  silver  nitrate  in  five  minutes.  When  dried  the 
tetanus  spores  will  live  several  years.  Sunlight  very  slowly 
kills  them.  Most  animals  are  susceptible  to  the  tetanus 
bacillus  or  its  toxins.  Rats  and  birds  are  the  least,  while 
horses  and  man  are  the  most  sensitive. 


BACILLUS  TETANI  107 

Tetanus  Antitoxin. — The  toxin  of  the  tetanus  bacillus  is 
one  of  the  most  virulent  poisons  known.  For  example, 
i  o  o  0*0  o  o  o  cubic  centimeter  or  GTsVoo  minim  has  been  known 
to  kill  a  mouse.  It  is  composed  of  two  parts,  one  the  major, 
with  a  primary  irritating  and  secondary  paralyzing  effect 
on  the  central  nervous  system,  and  a  minor  part  having  a 
solvent  action  upon  the  red  blood  cells.  These  poisons 
develop  both  in  wounds  and  on  laboratory  culture  media. 
The  methods  for  procuring  this  poison  are  essentially  those 
described  under  Diphtheria,  and  similar  methods  are  used 
to  immunize  horses  against  it.  The  antitoxin  is  in  the 
immunized  horse's  serum,  and  is  refined  and  used  in  the 
same  general  manner  as  diphtheria  antitoxin.  The  unit  in 
this  case  is  the  quantity  of  antitoxin  necessary  to  neutralize 
1000  times  the  smallest  dose  of  toxin  required  to  kill  a  guinea- 
pig  weighing  350  grams,  llf  ounces.  The  conditions  of 
administering  antitoxin  for  tetanus  are  somewhat  different 
from  those  in  diphtheria.  In  the  latter  the  poison  is  largely 
circulating  in  the  blood,  while  in  tetanus  some  of  it  is  at  the 
point  of  infection,  some  in  the  muscles  and  nerves  and  central 
nervous  system,  and  the  least  part  is  in  the  blood.  To  reach 
all  of  these  places  it  is  necessary  to  make  injections  into  the 
vein  and  under  the  skin  as  well.  The  surgeon  attempts  to 
reach  those  parts  first  which  have  been  affected  the  longest, 
to  halt  at  once  any  further  damage  there,  and  therefore 
methods  of  treatment  vary.  Antitoxin  is  sometimes  injected 
directly  into  the  nerves  in  order  that  some  may  neutralize 
what  toxin  is  remaining  in  them  along  their  length  or  in  their 
muscle  distribution.  In  severe,  rapidly  developing  cases  it 
may  be  injected  into  the  meningeal  space  or  directly  into  the 
brain  tissue. 

It  is  best  to  give  10,000  units  by  the  vein  and  repeat 
at  several-hour  intervals  until  symptoms  start  to  abate. 
The  sooner  after  the  symptoms  appear  that  antitoxin  is 
given  the  more  favorable  is  the  outlook.  Antitoxin  is  now 
given  freely  by  health  authorities,  to  all  who  receive  firearm 


108        THE    ACUTE    SELF-LIMITED    INFECTIONS 

wounds  about  July  4.  Every  man  wounded  in  the  Great 
War  receives  antitoxin  against  tetanus;  if  the  wound  be 
recent  a  smaller  dose  is  given  than  when  many  hours  have 
elapsed.  By  this  means  tetanus  has  been  practically  eradi- 
cated from  war  hospitals  caring  for  wounded. 

BACILLUS  TYPHOSUS. 

Typhoid  fever  or  enteric  fever  is  an  acute  infectious  dis- 
ease caused  by  the  Bacillus  typhosis  or  typhoid  bacillus 
circulating  in  the  blood  and  settling  in  the  various  organs, 
particularly  the  lymphatic  structures  of  the  small  intestines. 

The  bacteria  enter  the  body  lia  the  mouth  and  are  able 
to  pass  the  stomach  into  the  small  intestines.  Here  they 
are  taken  up  by  the  lymphatic  organs,  which  immediately 
begin  to  swell.  This  reaction  brings  more  blood  to  the  part 
and  the  circulation  soon  contains  the  germs.  The  incuba- 
tion period  is  that  time  elapsing  between  the  introduction 
of  the  typhoid  bacillus  into  the  alimentary  canal  and  the 
first  positive  signs  that  it  has  been  taken  up  and  disseminated 
by  the  blood  stream.  Then  there  are  gradually  increasing 
fever,  malaise,  a  relatively  slow  pulse,  distention  of  the 
abdomen,  diarrhea  or  constipation,  rose  spots,  and  other 
signs  of  the  true  infection.  The  incubation  is  about  two 
weeks.  The  bacteria,  while  not  true  pus-formers,  do  cause  a 
breaking  down  of  tissue.  This  is  characteristically  seen  in 
the  lymphatics  of  the  small  intestine  called  Peyer's  plaques. 
These  bodies  swell  toward  the  free  lumen  of  the  canal,  and 
the  center  finally  softens  from  the  effect  of  the  bacilli.  When 
the  softened  part  separates  and  is  removed,  a  ragged,  punched- 
out  ulceration  remains.  This  ulceration  may  be  progressive 
and  eat  into  bloodvessels,  causing  intestinal  hemorrhage  so 
common  in  this  disease.  If  the  ulceration  be  directed  out 
toward  the  peritoneal  surface  of  the  intestine,  perforation 
and  peritonitis  may  ensue.  The  presence  of  the  typhoid 
bacilli  and  their  toxins  in  the  organs,  notably  the  spleen, 


BACILLUS  TYPHOSUS  109 

causes  characteristic  changes  which  need  not  be  dwelt  upon 
here. 

Typhoid  fever  is  more  common  in  men  between  the  ages 
of  twenty  and  thirty- five  years.  Spring  and  autumn  are 
the  seasons  of  greatest  prevalence.  It  spreads  from  patient 
to  patient  usually  through  the  intervention  of  food  and  drink 
and  accidental  or  chronic  carriers.  Water  and  food  polluted 
by  flies  that  have  soiled  their  bodies  upon  excreta,  form  the 
greatest  sources  of  indirect  propagation.  Water  is  polluted 
by  the  dumping  of  sewage  containing  typhoid  germs  into  a 
water-course  used  as  a  drinking  supply.  Typhoid  bacilli 
can  live  within  a  particle  of  feces  over  the  winter,  so  that  the 
infection  of  a  water-course  in  the  spring  is  not  to  be  wondered 
at.  When  winter  breaks  up  the  spring  rains  wash  down  the 
hillsides,  sweeping  before  them  surface  collections  into 
streams.  The  greatest  danger,  however,  exists  when  towns 
empty  their  sewerage  systems  into  a  stream  from  which 
other  communities  lower  down  take  their  domestic  supply. 
This  means  of  spread  is  proved  by  the  fact  that  when  known 
infected  sewage  is  no  longer  dumped  into  a  water  supply 
typhoid  fever  ceases  to  be  prevalent  among  the  users  of  the 
water.  Ice  is  said  to  be  another  method  of  transmitting  this 
disease.  It  is  best  not  to  inculpate  the  ice  itself,  since  freezing 
kills  whatever  germs  are  not  squeezed  out  in  the  contraction 
of  the  water  when  becoming  solid,  but  rather  blame  the  dirty 
methods  of  cutting,  storing,  and  distributing.  Ice  not 
infrequently  becomes  covered  with  manure  and  earth  in 
storing  and  lading  for  distribution.  The  unwashed  hands 
of  the  ice-man  are  only  too  familiar.  When  ice  is  placed  in 
the  water  cooler  in  public  places  it  is  frequently  washed  under 
a  spigot  and  then  picked  up  in  the  hands  of  the  distributor. 
Typhoid  bacilli  do  not  multiply  to  any  considerable  extent 
in  water,  but  merely  remain  viable. 

Milk  is  a  profile  source  of  spread,  since  it  is  easy  for  the 
dairyman  with  a  case  of  typhoid  on  his  farm  to  infect  this 
product.  Fresh  milk  has  a  mild  restraining  effect  upon 


110       THE    ACUTE    SELF-LIMITED    INFECTIONS 

typhoid  germ  growth,  but  does  not  kill  many.  The  bacilli 
do  not  come  from  the  cow,  but  are  introduced  somewhere  in 
the  route  from  her  to  the  consumer.  Vegetables  grown  in 
ground  upon  which  infected  manure  or  water  has  been  spread 
may  carry  the  disease;  such  as,  for  instance,  water-cress, 
lettuce,  tomatoes,  or  others  that  are  eaten  raw.  Oysters 
fattened  in  water  contaminated  by  sewage  are  said  to  trans- 
mit the  disease. 

House-flies  may  settle  upon  human  excreta  in  out-houses 
or  toilets  or  in  sick-rooms,  and  by  walking  on  articles  intended 
for  food,  leave  behind  some  of  the  germs. 

The  personal  contact  of  nurse,  physician,  or  a  member 
of  the  family  must  never  be  underestimated  as  a  means  of 
direct  transmission.  Indeed,  it  is  looked  upon  by  some 
authorities  as  the  most  important  and  fruitful  method.  Upon 
bed-pans,  glasses,  eating  utensils,  bed  linen,  or  clothes  there 
may  be  a  few  bacilli  lurking,  which  can  easily  be  conveyed 
to  the  mouth  by  persons  handling  these  objects. 

The  typhoid  bacilli  may  lurk  in  the  body,  probably  in  the 
bile  passages,  for  a  long  time  after  the  attack.  For  this 
reason  disinfection  of  stools  and  urine  should  be  continued 
for  at  least  two  months  after  the  patient  is  well  or  until  the 
patient  has  been  declared  free  of  typhoid  organisms  by  the 
laboratory.  Such  people  as  may  spread  the  disease' by  this 
means  are  called  "carriers."  There  are  also  cases  on  record 
in  which  persons  who  never  suffered  with  typhoid  fever  have 
excreted  the  bacilli  in  their  stools.  It  is  probable  that  these 
persons  have  had  sufficient  resistance  to  overcome  intestinal 
disease,  but  the  germs  have  infested  the  bile  passages  and 
passed  down  them  to  be  mixed  with  the  excreta.  Two  such 
cases  are  known  to  the  writer,  one  of  which  had  a  history  of 
having  nursed  her  husband  in  a  fatal  attack  of  typhoid,  but 
whose  personal  history  is  free  of  any  illness  suggesting  this 
disease. 

Measures   for   preventing   infection    should    be   directed 
toward  killing  all  the  typhoid  bacilli,  not  such  a  difficult 


BACILLUS  TYPHOSUS  111 

task.  Infective  material  consists  of  feces,  urine,  expectora- 
tion, and  possibly  perspiration.  Any  of  these  may  infect 
bed  or  body  linen,  and  the  last  can  spread  the  bacilli  on 
dishes  or  hands.  All  discharges  should  be  received  in  carbolic 
acid  solutions,  well  mixed  and  allowed  to  stand  half  an  hour 
before  emptying  into  a  drain.  Clothing  of  all  kinds  should 
be  soaked  in  carbolic  or  corrosive  sublimate  solution  for  an 
hour,  and  then  boiled.  The  same  procedure  should  be  fol- 
lowed with  glasses  and  eating  utensils.  The  mouth  should 


FIG.  34. — Microscopic  field,  showing  the  top  of  a  hanging  drop  in  a  normal 
typhoid  culture.     (Park.) 


be  washed  or  wiped  with  boric  acid  solution  frequently.  A 
dish  of  bichloride,  1  to  2000,  should  be  convenient,  so  that 
the  nurse  or  visitor  may  cleanse  the  hands  frequently. 

The  typhoid  bacillus  is  an  organism  exerting  its  noxious 
power  by  means  of  poisons  contained  in  its  body  and  liberated 
upon  its  disintegration.  These  endocellular  poisons  are 
capable  of  calling  forth  a  reaction  upon  the  part  of  the  body 
which  results  in  some  antibody  formation.  Second  attacks 
of  typhoid  are  rare  and  the  reason  is  probably  that  a  sort 
of  active  immunity  is  gained  by  one  attack.  As  a  matter 


112        THE    ACUTE    SELF-LIMITED    INFECTIONS 

of  fact,  it  can  be  shown  by  laboratory  methods  that  blood 
after  typhoid  fever  has  more  power  to  destroy  the  bacilli 
than  before  the  attack;  that  is,  it  has  more  bacteriolysin  than 
is  possessed  by  the  blood  of  a  person  who  has  never  suffered 
from  typhoid. 

Widal  Test. — Far  more  important  antibodies  are  the 
agglutinins  used  extensively  in  the  diagnosis  of  the  disease. 
These  are  bodies  in  the  blood  which  when  brought  into 
contact  with  the  bacilli,  make  them  stop  moving  and  clump 
together.  To  use  this  for  diagnostic  purposes  a  fluid  culture 


FIG.  35. — Microscopic  field,  showing  the  top  of  a  drop  with  the  typhoid 
reaction.     (Park.) 

or  salt  solution  suspension  of  the  living,  actively  motile 
germ  is  prepared.  Some  blood  from  the  patient  is  obtained, 
the  clear  serum  collected  and  mixed  with  the  bacterial  sus- 
pension in  dilution  of  1  part  of  the  serum  to  20,  50,  100  or 
more  parts  of  the  bacterial  suspension.  These  dilutions  are 
used  because  sera  from  some  persons  entirely  free  from 
typhoid  will  clump  the  bacilli  in  low  dilution,  1  to  5  or  1  to 
10.  The  mixture  of  serum  and  bacteria  is  observed  under 
the  microscope  after  they  have  stood  together  for  a  definite 
time,  and  the  presence  of  clumping,  with  loss  of  movement, 


BACILLUS  TYPHOSUS  113 

noted.  In  case  this  occurs  typhoid  is  present.  This  agglu- 
tination reaction  is  called  the  Widal  test,  and  is  positive  in 
about  95  per  cent,  of  all  cases  (see  Figs.  33  and  34.) 

Cultures. — It  is  also  of  aid  in  the  diagnosis  of  typhoid  to 
make  a  blood  culture.  This  consists  in  withdrawal,  under 
sterile  conditions,  of  blood  from  a  vein,  placing  it  into  suit- 
able culture  medium,  and  keeping  it  at  body  heat  in  the 
incubator.  If  typhoid  bacilli  be  present  they  will  grow  so 
that  we  may  isolate  and  identify  them.  The  bacilli  may  be 
isolated  also  from  the  feces  and  urine  during  an  attack,  and 
as  mentioned  above,  for  a  long  time  afterward  in  the  case 


FIG.  36. — Typhoid  bacilli  from  nutrient  gelatin.      X  1100  diameters. 

(Park.) 

of  carriers.  The  methods  for  isolation  are  tedious  and 
difficult,  and  need  not  be  described  here.  Many  technics 
have  been  devised  to  hasten  work  on  epidemics  and  carriers, 
but  none  is  as  yet  perfect. 

The  isolation  of  typhoid  bacilli  from  blood,  feces  or 
urine  is  necessary  for  a  certain  diagnosis  of  the  disease 
in  persons  who  have  received  antityphoid  vaccines,  as  the 
prophylactic  injections  cause  the  appearance  of  agglutinin 
enough  to  give  the  Widal  reaction. 

Morphology. — The  typhoid  bacillus  is  a  motile  rod  2~5Wo  to 
grro  incn  long  and  5-0000  to  scoop  incn  wicle,  witn  rounded 
ends,  growing  in  long  threads  at  times.  Its  motility  is  due 
8 


114        THE    ACUTE    SELF-LIMITED    INFECTIONS 

to  flagella  all  around  its  cell  wall.  It  forms  no  spores.  It 
stains  easily,  oftentimes  more  densely  at  the  rounded  ends. 
It  grows  in  the  presence  or  absence  of  oxygen,  best  at  37°  C. 
or  98°  F.,  but  also  at  room  temperature.  It  is  killed  by 
heating  at  60°  C.  or  142°  F.  for  five  minutes,  or  to  52°  C.  or 
126°  F.  for  ten  minutes  when  in  water  suspension.  It  usually 
dies  rapidly  when  dried,  but  occasionally  lives  for  some 
weeks.  It  is  killed  in  watery  suspension  by  1  per  cent, 
carbolic  acid  or  1  to  1000  bichloride  in  ten  minutes.  Its 
characters  in  laboratory  culture  media  are  not  easy  to 


FIG.  37. — Typhoid  bacillus  with  faintly  stained  flagella.     (Loffler's  method.) 

(Park.) 


describe,  and  indeed  the  trained  observer  is  often  puzzled 
to  identify  it.  Suspected  cultures  are  usually  subjected  to 
the  Widal  test,  using  the  blood  of  a  patient  with  typhoid 
fever,  and  known  to  clump  a  true  typhoid  bacillus.  The 
bacillus  belongs  to  the  so-called  typhocolon  group  (see 
p.  157).  The  lower  animals  do  not  develop  typhoid  fever 
when  inoculated  with  this  germ,  but  die  of  septicemia,  usually 
with  peritonitis. 

Immunization. — An    antitoxin    to    the    typhoid    bacillus 
cannot  be  produced,  but  attempts  at  active  immunization 


BACILLUS  TYPHOSUS  115 

have  been  made  with  success.  These  attempts  take  the 
direction  of  injecting  the  bacilli  in  such  a  form  that  they 
cannot  produce  the  disease,  but  yet  set  up  some  resistance 
to  it  comparable  to  that  acquired  by  passing  through  a 
spontaneous  attack.  The  bacilli  are  prepared  like  the  vac- 
cines or  bacterins  described  on  p.  69,  and  injected  under  the 
skin.  A  slight  fever  may  result,  but  no  further  bad  effects 
have  been  noted.  All  symptoms  are  over  in  twenty-four 
hours  after  each  injection.  The  bacteria  are  introduced 
three  times  in  quantities  of  500,000,000,  1,000,000,000  and 
1,000,000,000  at  ten-day  intervals.  The  immunity  resulting 
is  supposed  to  last  about  two  years.  This  vaccine  method 
is  well  adapted  for  and  most  used  by  armies  going  into 
camps.  The  results  in  our  army  and  that  of  Great  Britain 
have  been  very  encouraging.  It  should  be  taken  by  nurses 
doing  army  nursing  or  seeing  many  typhoid  cases. 

Colonel  Russell,  U.  S.  A.,  concludes  his  investigations 
into  the  theory  and  practice  of  antityphoid  vaccination  as  a 
prophylactic  as  follows : 

1.  Antityphoid  vaccination  in  healthy  persons  is  a  harm- 
less procedure. 

2.  It  confers  almost  absolute   immunity   against   infec- 
tion. 

3.  It  is  the  principal  cause  of  the  immunity  of  our  troops 
against  typhoid  in  the  recent  Texas  maneuvers. 

4.  The  duration  of  the  immunity  is  not  yet  determined, 
but  is  assuredly  two  and  one-half  years  and  probably  longer. 

5.  Only  in  exceptional  instances  does  its  administration 
cause  an  appreciable  degree  of  personal  discomfort. 

6.  It   apparently   protects   against   the   chronic   bacillus 
carrier  and  is  at  present  the  only  means  by  which  a  person 
can  be  protected  against  typhoid  under  all  conditions. 

7.  All  persons  whose  profession  or  duty  involves  contact 
with  the  sick  should  be  immunized. 

8.  The  general  vaccination  of  an  entire  community  is 
feasible  and  could  be  done  without  interfering  with  general 


116       THE    ACUTE    SELF-LIMITED    INFECTIONS 

sanitary  improvements,  and  should  be  urged  whenever  the 
typhoid  rate  is  high. 

By  the  use  of  this  prophylactic,  typhoid  fever  has  prac- 
tically disappeared  from  the  United  States  Army. 

Vaccines  have  also  been  used  during  an  attack  of  typhoid, 
but  the  results,  while  satisfactory  to  some  observers,  cannot 
be  said  to  be  generally  acceptable. 

Paratyphoid  Fever.— There  is  a  variety  of  enteric  fever 
called  paratyphoid  fever.  This  is  caused  by  the  Bacillus 
paratyphosus,  an  organism  closely  allied  to  the  true  typhoid 
bacillus  and  only  separated  from  it  by  its  ability  to  ferment 
certain  sugars  and  the  quantity  of  acid  it  produces  under 
artificial  conditions.  In  paratyphoid  fever,  however,  the 
blood  will  not  clump  (agglutinate)  the  true  typhoid  bacillus, 
but  does  have  such  an  action  upon  the  paratyphoid  bacillus. 
In  this  form  of  fever  the  course  is  shorter,  the  attack  is 
milder,  and  complications  are  much  less  frequent.  There  is 
usually  no  ulceration  of  Peyer's  plaques  and  therefore  hemor- 
rhage from  the  bowel  is  of  extreme  rarity.  It  is  nevertheless 
an  infectious  disease,  entirely  comparable  in  its  origin,  course, 
transmission,  and  epidemic  character  to  true  typhoid  fever, 
and  the  same  precautions  of  disinfection  must  be  observed. 
Paratyphoid  infections  are  due  to  two  closely  related  sub- 
varieties;  they  occur  at  times  in  epidemics  like  typhoid; 
they  are  amenable  to  the  same  prophylactic  measures. 

It  is  now  the  practice  to  give  a  single  vaccine  with  all  three 
organisms  in  it,  typhoid  and  paratyphoid  A  and  B  bacilli; 
this  protects  against  all  these  infections.  This  "  triple  vac- 
cine" is  now  given  in  three  doses  ten  days  apart,  but  it  is 
expected  that  this  procedure  will  be  shortly  superseded  by  a 
single  dose  of  the  required  number  of  germs  suspended  in  oil, 
a  medium  which  holds  the  organisms  in  good  suspension  and 
permits  a  slow  absorption  conducive  to  a  thorough  immuni- 
zation. All  typhoid  and  paratyphoid  infections  have  been 
practically  eradicated  in  the  armies  at  war. 


PLATE   IV 


Bacterium   Influenzas  in  Sputum.     (Abbott.) 


BACTERIUM  INFLUENZA  117 

MICROCOCCUS  MELITENSIS. 

Malta  fever  is  an  acute  infectious  septicemic  disease, 
endemic  along  the  Mediterranean,  following  a  course  similar 
to  typhoid  fever,  but  usually  of  less  serious  nature.  It  is 
caused  by  the  Micrococcus  melitensis.  Goats  harbor  the 
organisms  and  pass  them  out  through  the  milk,  an  important 
food  in  Malta.  Persons  can  be  infected  by  introduction 
through  a  wound.  It  is  probably  not  transmitted  from  man 
to  man.  The  diagnosis  is  made  by  means  of  blood  cultures 
or  by  the  agglutination  test.  The  bacteria  are  of  rather 
elongated  shape,  by  some  observers  taken  to  indicate  that 
they  are  bacilli.  They  are  about  yyj-oo  inch 'long,  single  or 
in  pairs.  No  motility  is  seen,  and  no  spores  are  formed.  They 
stain  easily  and  grow  well  in  ordinary  media  at  37°  C.  or  98° 
F.  Monkeys  are  the  only  animals  which  can  be  artificially 
infected.  Vaccines  of  dead  cultures  may  be  used.  The  bacilli 
are  killed  by  the  same  methods  as  the  typhoid  bacillus. 

BACTERIUM  INFLUENZA. 

Influenza  is  also  called  la  grippe  or  grip,  and  is  an  acute 
catarrhal  disease  usually  involving  the  mucous  membrane  of 
the  upper  respiratory  tract,  but  also  penetrating  to  the  deeper 
parts.  Its  causative  bacterium  is  the  probable  Bacterium 
influenzcB  or  the  influenza  bacillus.  The  disease  is  one  which 
appears  in  epidemic  form  usually,  but  sporadic  cases  also 
occur.  The  organisms  are  carried  in  the  nose  and  throat  and 
communicated  to  others  in  the  fine  particles  coughed  or  spat 
out.1  They  lodge  on  the  mucous  surfaces  and  produce  an 
inflammation  through  which  the  poisons  are  absorbed.  The 
rods  themselves  do  not  usually  enter  the  blood  stream,  but 
they  may  do  so,  as  is  attested  by  the  fact  that  there  are 
influenzal  forms  of  pleuritis  and  pericarditis,  diseases  prob- 
ably not  due  to  an  extension  by  continuity.  Influenzal 
pneumonia  occurs  when  the  bacteria  penetrate  to  the  lung 


118        THE    ACUTE    SELF-LIMITED    INFECTIONS 

tissue  proper.  It  is  comparable  in  development  to  the 
pneumonia  caused  by  the  pneumococcus.  The  bacillus  may 
at  times  form  pus. 

A  very  important  and  highly  fatal  form  of  influenzal 
infection  is  meningitis  due  to  a  blood  distribution  of  the 
organisms  in  cases  of  pneumonia  or  other  local  lesion,  but  at 
times  arising  without  previous  history  of  illness.  The  disease 
is  clinically  similar  to  epidemic  meningitis  and  the  fluid  in  the 
meningeal  spaces  is  likewise  purulent. 

The  attack  of  influenza  runs  an  acute  course.  It  leaves 
but  a  transient  immunity,  and  one  attack  is  said  actually 
to  predispose  to  another  when  the  individual  is  exposed 
subsequently.  As  complications  of  influenza  of  the  upper  air 
passages  we  may  have  pus  in  the  sinuses  about  the  nose,  or 
otitis  media. 

While  influenza  is  an  acute  disease  and  the  bacteria  are 
actively  virulent  during  an  attack,  it  is  believed  that  they 
remain  in  the  upper  air  passages  in  abeyance  and  not  produc- 
ing disease  for  long  periods  after  the  acute  symptoms  have 
subsided.  When  they  are  received  in  sputum  particles  upon 
the  nose  or  mouth  of  another  person  not  resistant  to  them, 
they  regain  their  activity  and  inflame  the  parts.  It  is  said 
that  they  may  remain  in  the  lung  tissue  for  a  long  time  until 
some  reduction  of  the  person's  resistance  permits  the  light- 
ing up  of  a  pneumonia. 

With  these  facts  in  mind  it  is  not  difficult  to  understand 
how  sporadic  cases  occur  and  how  the  disease  spreads  rapidly 
from  one  patient  to  another.  The  bacilli  get  to  work  on  the 
mucous  membranes  rapidly,  and  the  incubation  period  is 
short,  three  days  at  the  longest.  Epidemics  have  been  known 
to  spread  over  whole  continents  in  a  season.  Many  observers 
believe  that  other  organisms,  notably  streptococci,  help  in  the 
production  of  these  acute  influenzal  colds.  It  is  undoubtedly 
true  that  the  influenza  bacillus  is  seldom  found  in  pure  culture, 
that  is,  in  absence  of  some  other  organism  with  pathogenic 
properties.  The  bacilli  are  found  in  the  excretions  and 


BACTERIUM  INFLUENZA  119 

secretions  from  the  nose,  mouth,  and  lungs.  All  excretion 
should  be  received  into  carbolic  acid  solution,  and  the  mouth 
and  nose  frequently  douched  with  a  mild  antiseptic.  The 
nurse  and  members  of  the  family  should  use  care  with  the 
nose  and  mouth  in  frequent  rinsing  with  weak  antiseptics, 
such  as  hydrogen  peroxide.  For  diagnosticating  this  disease 
smears  and  cultures  are  made  from  some  of  the  glistening 
mucus  at  the  back  of  the  throat  or  a  good  specimen  of  sputum 
coughed  from  the  lungs.  The  smears  on  slides  are  stained 
with  appropriate  dyes.  Under  the  microscope  the  delicate 
rods  are  found  in  pairs  on  end,  lying  in  groups  or  within  the 
pus  and  epithelial  cells.  In  cultivating  these  organisms  media 
containing  whole  blood  or  blood  coloring  matter,  hemoglobin, 
must  be  used.  They  will  not  grow  in  the  absence  of  the  latter, 
and  the  colonies  upon  solid  media  containing  it  are  rather 
characteristic.  During  an  attack  the  bacteria  produce  some 
agglutinins  in  the  blood  and  the  agglutination  or  clumping 
test  may  be  used  with  them.  This  is  not  highly  practical 
and  seldom  used. 

The  influenza  organism  is  a  very  minute  rod  with  pointed 
or  round  ends  and  commonly  lying  in  pairs  with  their  ends 
together.  They  do  not  move  nor  form  spores.  They  measure 
about  50000  inch  long  and  TToVoo  to  75000  inch  wide. 
They  require  oxygen  for  growth,  which  occurs  on  blood- 
containing  media  as  fine  dew  drop-like  colonies.  Their  general 
biological  characters  offer  fine  details  not  needed  here.  They 
require  body  heat,  37.5°  C.  or  98°  F.,  for  development,  and 
are  killed  at  50°  C.  or  122°  F.  for  ten  minutes;  60°  C.  or 
142°  F.  kills  at  once.  They  die  in  twelve  hours  if  dried  in 
sputum,  but  may  live  without  multiplication  for  several 
days  in  moist  sputum  at  ordinary  temperature.  Five  per 
cent,  carbolic  acid  kills  them  in  well-mixed  sputum  in 
five  minutes.  For  animals  this  bacterium  is  not  very  patho- 
genic. Rabbits  and  monkeys,  if  injected  into  the  vein  with  a 
pure  culture  exhibit  very  quickly  signs  of  an  intoxication, 
which  rapidly  passes  away.  Monkeys  may  get  an  acute  cold 


120       THE    ACUTE    SELF-LIMITED    INFECTIONS 

by  the  direct  application  of  the  bacilli  to  the  abraded  mucous 
membrane  of  the  nose.  For  the  treatment  of  acute  influenzal 
colds  there  is  no  practicable  specific  therapy  by  the  use  of 
antisera  or  bacterins.  When,  however,  there  is  a  prolonged 
catarrh  of  sinuses,  larynx,  or  bronchi,  or  when  it  can  be 
shown  that  a  person  is  harboring  the  bacilli,  it  is  perfectly 
feasible  to  employ  dead  organisms  as  a  bacterin,  using, 
wherever  possible,  a  culture  from  the  patient.  This  is  prac- 
tically never  in  pure  cultures  and  mixed  vaccination  is  the 
rule.  For  pneumonia,  pleurisy,  and  so  forth  we  know  nothing 
of  the  practical  nature  of  antiserum,  but  for  meningitis  it  has 
been  found  to  have  some  curative  effect.  It  is  introduced 
into  the  spinal  canal  after  withdrawal  of  some  fluid  to  make 
room  for  it.  It  is  made  by  injecting  horses  with  increasing 
numbers  of  the  bacilli  and  separating  the  serum  as  for 
diphtheria  antitoxin. 


BACILLUS  PESTIS. 

Bubonic  plague,  or  "the  plague"  or  "pest,"  is  an  acute 
infectious  disease  caused  by  the  Bacillus  pestis,  and  char- 
acterized by  high  fever,  suppuration,  swelling  of  the  lymph 
glands,  and  a  severe  grade  of  bacteremia.  In  the  so-called 
pneumonic  form,  a  pulmonary  inflammation  dominates  the 
clinical  picture,  but  the  infective  nature  of  the  disease  is  the 
same.  Occasionally  in  very  severe  attacks,  subcutaneous 
hemorrhages  occur;  this  is  called  "black  death."  The 
commoner  or  lymph  gland  form  occurs  when  the  bacteria 
gain  entrance  by  flea  bites,  skin  cracks  or  wounds,  while  the 
pneumonic  type  follows  inhalation  of  the  germs. 

The  bacteria  enter  chiefly  through  the  skin  by  way  of 
minute  wounds,  or,  as  was  shown  in  India,  by  the  bite  of  a 
rat  flea.  Rats  and  mice,  indeed  all  rodents,  are  susceptible  to 
plague,  it  practically  being  endemic  among  them  in  certain 
countries,  and  they  contract  it  from  biting  the  living,  feeding 


PLATE   V 


Bacillus  of  Bubonic  Plague.     (Abbott.) 

A,    in  pus    from   suppurating   bubo;   B,    the   bacillus  very   much 
enlarged  to  show  peculiar  polar  staining. 


BACILLUS  PESTIS  121 

on  the  dead,  soiling  themselves  on  dressings  or  excreta,  but 
principally  by  their  parasitic  fleas.  When  infected  they  have 
great  numbers  of  bacilli  in  their  blood,  thus  easily  passing 
them  on  to  fleas  that  bite  them.  The  fleas  then  pass  the  dis- 
ease to  other  rats  and  to  man.  Furthermore,  rats  may  vomit, 
defecate,  and  die  where  they  can  infect  objects  later  handled 
by  persons.  The  rats  are  said  to  transmit  the  disease  also  by 
biting  people.  In  epidemic  times  the  ground  becomes  in- 
fected, and  persons  going  bare- foot  may  be  infected.  By 
any  of  the  skin-wound  methods,  the  germs  enter  the  sub- 
cutaneous tissue,  are  carried  to  the  nearest  lymph  glands, 
where  they  set  up  inflammation  and  pus,  which  is  frequently 
discharged  by  rupture  through  the  skin.  The  bacteria  enter 
the  blood  stream  and  produce  a  septicemia. 

In  the  pneumonic  form  the  bacteria  are  inhaled  and  set 
up  a  pneumonia  not  unlike  that  produced  by  ordinary  cocci. 
Here,  again,  there  may  be  suppuration  and  septicemia. 

The  bacilli  produce  the  characteristic  results  chiefly  by 
means  of  their  endotoxins,  little  or  no  separable  poisons 
being  formed.  There  is  no  difference  in  the  bacteria  or  their 
products  in  the  two  forms,  these  simply  depending  upon  the 
mode  of  entry.  The  mortality  of  this  disease  is  very  high, 
due  to  the  rapid  progress  made  after  the  disease  gains  a  foot* 
hold.  The  incubation  is  three  to  seven  days.  The  bacteria 
are  present  in  the  blood,  pus,  and  sputum  in  enormous 
numbers.  They  may  be  also  in  dejecta.  Many  suppose 
them  to  be  in  the  breath,  but  this  is  probably  erroneous. 
They  are  in  the  droplets  of  saliva  expelled  by  coughing, 
sneezing,  and  talking.  It  is  customary  in  times  of  epidemics 
to  go  about  with  a  towel  over  the  nose  and  mouth,  with  the 
feet  and  ankles  well  bound,  and  all  surfaces  covered.  Sputum, 
urine,  and  feces  should  be  received  into  5  per  cent,  carbolic 
acid  and  allowed  to  remain,  well  mixed,  for  twro  hours.  Dress- 
ings from  ulcerated  surfaces  must  be  burned.  Doors  and 
windows  must  be  screened  against  flies  and  mosquitoes. 
The  room  must  be  rat-  and  mouse-free.  After  death  formal- 


122        THE    ACUTE    SELF-LIMITED    INFECTIONS 

dehyde  or  carbolic  acid  solution  is  to  be  injected  into  the  body 
entrances  and  applied  about  the  body  on  the  winding  sheet. 

For  diagnosticating  this  disease  an  abscess  is  punctured, 
the  pus  withdrawn,  and  slide  smears  and  cultures  are  made. 
The  bacilli  are  found  in  countless  numbers.  Cultivation  on 
ordinary  media  is  simple.  A  blood  culture  will  also  reveal 
their  presence.  At  death  bacteria  will  be  found  in  practically 
every  organ  in  the  body.  In  the  pneumonic  form  an  examina- 
tion of  sputum  reveals  enormous  numbers  of  the  character- 
istic organisms. 

The  plague  bacillus  is  a  short  plump  rod,  1 7Q00  to  ±  3Q00 
inch  long  by  50Q00  to  30000  inch  wide.  It  does  not  move 
nor  form  spores.  It  grows  best  at  35°  C.  or  92°  F.  It  is 
stained  with  reasonable  ease,  displaying  a  peculiar  picture. 
The  bacilli  are  short,  thick  rods  with  rounded  ends.  The  end 
section  stain  much  more  densely  than  the  middle  part,  called 
bipolar  staining.  These  rods  may  grow  longer  and  appear 
in  pairs  or  short  chains.  They  are  killed  by  60°  C.  or  142°  F. 
in  ten  minutes,  or  by  boiling  water  in  two  minutes.  They 
resist  drying  for  two  or  three  days  under  natural  conditions, 
but  when  drying  is  hastened  by  artificial  means,  they  live 
only  a  few  hours.  They  resist  cold  and  freezing  for  a  long  time, 
perhaps  a  month.  Sunlight  destroys  them  in  five  hours.  In 
pus  or  sputum  they  may  live  a  few  weeks,  but  in  cadavers 
they  have  been  found  after  several  months.  Chemicals 
kill  them  as  follows:  5  per  cent,  carbolic  acid  and  1  to  1000 
bichloride  in  ten  minutes.  Animals  are  usually  susceptible 
to  Bacillus  pestis,  particularly  guinea-pigs  and  rats,  and  it  is 
said  that  simple  rubbing  of  the  germs  on  the  skin  of  these 
beasts  will  produce  the  infection.  It  is  similar  to  the  human 
disease. 

Plague  Serum. — The  poison  of  Bacillus  pestis  is  largely 
intracellular.  It  has  been  possible  to  get  an  antiserum  from 
horses  which  will  destroy  the  bacteria  and  can  be  used  thera- 
peutically.  The  bacteria  grown  in  the  laboratory  are  killed 
by  moderate  heat  and  injected  into  animals.  The  injections 


SPIRILLUM  CHOLERA  ASIATICS  123 

are  continued  until  very  large  doses,  fatal  to  unprepared 
animals,  are  withstood.  The  serum  now  has  properties  which 
will  neutralize  the  endotoxins  of  the  plague  bacillus,  and 
is  called  a  bactericidal  serum.  It  is  said  to  have  also  some 
antitoxic  properties  that  neutralize  the  small  amount  of  extra- 
cellular poison  of  this  organism.  This  serum  is  used  for  treat- 
ment during  the  attack  or  for  immunizing  those  exposed. 
The  serum  is  injected  under  the  skin  for  preventive  purposes, 
but  during  an  attack  it  is  well  to  give  it  into  the  circulation. 
Not  only  is  this  passive  immunity  made  use  of,  but  for 
prevention  of  infection,  plague  bacilli  whose  pathogenic 
properties  are  destroyed  by  heat  are  also  injected  precisely 
as  has  been  described  for  typhoid  fever.  This  "vaccine" 
prophylactic,  and  one  of  the  first  of  such  procedures,  gives  an 
immunity  for  a  few  months.  Thus  there  is  an  active  immuni- 
zing therapy  for  plague,  and  passive  immunizing  substances 
can  be  added  to  the  patient's  own  defences.  Immunity 
against  a  subsequent  attack  always  follows  plague. 

SPIRILLUM  CHOLERA  ASIATICS. 

Cholera  is  an  acute  inflammatory  disease  of  the  small 
intestines  characterized  by  profuse  watery  stools,  a  profound 
prostration,  muscular  pains,  and  high  fever.  It  is  caused  by 
the  Spirillum  choleras  asiaticce  or  cholera  spirillum  or  vibrio. 
The  bacteria  enter  the  body  only  through  the  mouth,  and 
settle  upon  the  mucous  membrane  of  the  lower  part  of  the 
small  intestine.  This  they  penetrate  only  as  far  as  the 
deeper  layers  of  the  innermost  coat  of  the  tube,  and  by  their 
growth  cause  a  shedding  of  the  lining.  The  shreds  of  the 
desquamated  mucous  membrane  pass  off  with  the  watery 
discharges  and  cause  the  characteristic  "rice-water"  stools. 
The  bared  and  congested  surface  permits  absorption  of  the 
poisons  of  the  spirillum,  the  body  of  which  does  not  itself 
enter  the  blood  stream.  The  poison  quite  frequently  has  a 
depressing  action  upon  the  heart  muscle.  It  is  not  quite 


124       THE    ACUTE    SELF-LIMITED    INFECTIONS 

certain  whether  or  not  this  is  a  wholly  extracellular  toxin  or 
combined  closely  with  the  bacterial  bodies.  It  is  probably 
mostly  of  the  latter  character,  an  endotoxin  separated  upon 
the  disintegration  of  the  germ  cells. 

Cholera  is  a  disease  transmitted  almost  exclusively  by 
polluted  water,  although  food  infected  with  bacteria  may, 
of  course,  transmit  it.  Water  is  contaminated  by  dejecta  of 
cholera  patients,  and  the  vibrio  leaves  the  patient  in  no  way 
but  with  feces  and  vomitus.  Large  numbers  of  vibrios  are 
present  in  the  feces  early  in  the  attack.  Later  they  rapidly 
decrease,  but  do  not  disappear  from  the  gut  and  feces,  and 
may  continue  to  come  away  in  small  numbers  for  many 
months  (the  carrier  state).  In  such  cases  they  naturally 
pollute  anything  with  which  the  dejecta  come  in  contact. 
They  do  not  live  long  in  nature,  however,  and  regulations 
can  be  made  to  kill  them.  Flies  having  soiled  themselves 
upon  cholera  excreta  may  carry  the  germs.  Vegetables  may 
be  soiled  from  water.  Personal  contact  and  handling  of 
clothes  from  patients  have  the  same  value  in  transmission  of 
cholera  as  for  typhoid  fever.  As  the  organisms  leave  the  body 
only  with  the  feces,  measures  should  be  taken  to  disinfect 
them,  and  anything  likely  to  be  soiled  with  them.  The  feces 
should  be  received  into  5  per  cent,  carbolic  acid  solution. 
The  buttocks  and  anus  should  be  wiped  with  1  to  1000  bichlor- 
ide solution.  Clothes  or  bedding,  glasses,  utensils,  and  other 
objects  should  be  soaked  in  these  solutions.  Boiling  when 
possible  is  advisable.  A  disinfecting  hand  lotion  should  be 
constantly  used  by  the  attendants.  It  is  necessary  to  con- 
tinue disinfection  of  stools  for  varying  periods  after  an  attack, 
since  bacteria  lurk  in  the  depths  of  the  intestinal  mucosa,  and 
are  excreted  long  after  the  acute  symptoms  have  disappeared. 
As  in  typhoid  fever  it  has  been  found  that  contacts  to  cholera 
patients  may  carry  the  germs  without  having  the  disease; 
such  persons  may  transfer  the  disease  to  other  localities. 
Feces  should  be  disinfected  until  declared  bacteriologically 
free  from  the  vibrios. 


SPIRILLUM  CHOLERA  ASIATICS  125 

Cholera  is  diagnosticated  bacteriologically  by  cultivation  of 
the  stools.  The  organisms  are  present  in  almost  pure  culture, 
and  can  be  made  to  grow  quite  easily.  There  are  several 
other  spirilla  of  similar  form  and  manner  of  growth,  and  some- 
times delicate  biological  tests  (see  below)  are  necessary. 
Agglutination  tests  may  be  used  in  this  disease,  as  some 
clumping  power  is  acquired  by  the  blood  during  an  attack. 
Another  antibody,  a  bacteriolysin,  is  formed,  which  has  the 
power  of  dissolving  the  cholera  spirilla.  Animals  injected 
with  the  cholera  organisms  also  acquire  this  power.  If  a 
guinea-pig  be  injected  with  spirilla  up  to  a  point  where  it  will 
resist  large  numbers,  its  blood  serum  will  dissolve  the  living 
organisms  either  in  the  test-tube  or,  what  is  better,  within  the 
abdominal  cavity  of  another  guinea-pig.  In  the  latter  case 
the  antiserum  from  the  prepared  guinea-pig  and  living  rods 
are  mixed  and  injected  together  into  the  peritoneal  cavity. 
The  rods  are  devitalized  and  the  pig  lives,  although  another 
animal  receiving  the  organisms  in  like  quantity,  but  without 
serum,  will  die.  This  is  the  method  suggested  which  can  be 
used  to  identify  suspected  cultures,  using  as  the  protective 
blood  serum  that  from  an  animal  previously  treated  with 
known  cholera  germs. 

The  cholera  spirillum  is  a  curved  organism  something  the 
shape  of  a  comma,  and  is  sometimes  called  the  comma 
bacillus.  One  end  is  apt  to  be  thicker  than  the  other.  It 
sometimes  appears  like  an  S  when  two  are  joined  on  end. 
Long  filaments  may  be  seen  in  fluids.  In  old  laboratory 
cultures  it  may  appear  as  a  short,  straight  rod  or  club.  It  is 
actively  motile  by  means  of  a  long  single  flagellum  on  the  end. 
No  spores  are  formed.  It  measures  from  8~oVo  ^°  5  0*0  o 
inch  in  length  by  75Q00  inch  in  width.  It  is  not  easy  to 
measure  since  spirilla  are  not  simple  curves  but  spirals.  It 
does  not  stain  with  great  ease,  but  a  weak  watery  solution 
of  fuchsin  is  the  best.  It  grows  best  in  the  presence  of  oxygen 
at  37.5°  C.  or  98°  F.,  but  may  grow  at  ordinary  temperatures. 
It  has  the  power  of  digesting  gelatin  and  solidified  blood  serum 


126        THE    ACUTE    SELF-LIMITED    INFECTIONS 

but  does  not  clot  milk.  It  resists  60°  C.  or  142°  F.  for  one 
hour,  but  boiling  kills  at  once.  It  multiplies  at  the  tempera- 
ture of  foodstuffs,  and  freezing  does  not  destroy  it  under  three 
days.  Drying  kills  certainly  in  twenty-four  hours  in  diffuse 
light.  Sunlight  kills  within  one  hour.  The  figures  indicate 
some  resistance  to  heat  and  light,  but  against  chemicals  this 
is  not  maintained;  1  to  10GO  bichloride  is  fatal  in  ten  minutes; 
1  per  cent,  carbolic  acid  a  little  longer;  lime  in  any  form  is 
rapidly  fatal  to  the  spirillum. 


FIG.  38. — Spirillum  of  Asiatic  cholera:  /,  stained  by  ordinary  method; 
//,  stained  to  show  flagella.     (Abbott.) 


Animals  do  not  contract  cholera  either  spontaneously  or 
artificially,  but  they  may  be  killed  by  the  germs  or  their 
poisons.  The  active  acquired  immunity  they  get  by  repeated 
injections  has  been  described.  It  has  not  been  found  practical 
to  obtain  any  serum  from  animals  which  can  be  injected  into 
human  beings  as  a  treatment.  Dead  spirilla,  however,  can 
be  injected  into  well  persons  as  a  protective  measure, 
precisely  as  is  done  for  typhoid  and  plague,  and  with  good 
results. 


BACILLUS  DYSENTERIC  127 


BACILLUS  DYSENTERLffi. 

Dysentery  occurs  in  two  forms — the  bacillary  type  and  the 
amebic  type.  The  former  is  caused  by  bacteria,  while  the 
latter  is  a  protozoon  disease  (see  Chppter  XIV).  Bacillary 
dysentery  is  an  acute  infectious  disease,  its  chief  lesion  being 
a  violent  inflammation  of  the  lining  of  the  large  intestines. 
The  disease  is  caused  by  the  Bacillus  dysentericB  or  dysentery 
bacillus.  It  is,  however,  better  to  say  that  a  group  of  organ- 
isms under  this  name  gives  rise  to  it  because  there  are  many 
varieties  with  different  chemical  and  se  mm  reactions,  produc- 
ing attacks  of  varying  severity.  Their  general  pathogenic 
and  etiological  effects  may  be  discussed  together,  however. 
The  usual  ileocolitis  of  children  is  not  due  to  the  dysentery 
bacillus,  but  some  members  of  the  dysentery  group  have  been 
found  responsible  for  small  epidemics  of  diarrhea  among 
children. 

In  cholera  the  chief  lesions  are  in  the  lower  small  intestine, 
but  otherwise  the  two  diseases  have  many  things  in  common. 

The  bacilli  enter  probably  only  by  the  mouth  in  food  and 
drink  infected  with  feces,  handling  by  persons  with  soiled 
hands  or  by  flies,  and  pass  through  the  alimentary  tract  to 
their  organ  of  predilection,  the  colon.  Here  they  penetrate  the 
mucous  lining  to  its  deeper  layers,  causing  violent  irritation. 
They  may  get  deeper  into  the  wall  or  even  to  the  glands 
draining  the  colon,  but  not  into  the  blood.  The  inflammation 
gives  rise  to  diarrhea  which  passes  from  feculent  to  mucus, 
to  bloody  mucus,  and  may  be  almost  wholly  blood.  These 
effects  are  due  to  the  effort  of  the  colonic  wall  to  rid  itself  of 
the  poisons  and  the  body  seems  to  choose  this  method  to  free 
itself  of  the  intruder.  This  fact  is  further  shown  when  we 
inject  susceptible  small  animals  with  the  poisons,  for  a  con- 
gestion of  the  colon  and  diarrhea  result,  although  no  living 
organisms  are  present.  The  poisons  of  the  dysentery  bacilli 
are  probably  both  extra-  and  intracellular,  the  latter  being 
more  abundant.  The  toxic  effect,  therefore,  is  exerted  by  the 


128       THE    ACUTE    SELF-LIMITED    INFECTIONS 

existence  of  the  germs  in  the  mucous  membrane  giving  off 
poisonous  products  of  their  life,  and  to  a  greater  degree  by 
the  poisons  liberated  upon  their  disintegration.  The  poisons 
are  absorbed  into  the  blood,  giving  rise  to  an  irregular  fever 
in  which  sudden  drops  are  common.  This  sudden  fall  of 
temperature  may  be  observed  in  animals  receiving  doses  of 
the  poison. 

Dysentery  is  transmitted  like  other  diarrheal  disorders, 
that  is,  by  the  pollution  of  food  and  drink  by  discharges 
of  patients,  since  the  germs  leave  the  body  only  by  the  feces. 


'    *.  f^ 

• -%  r    y     ' 


FIG.  39.— Dysentery  bacilli.     X  1000  diameters.     (Park.)! 

Disinfection  of  excreta,  clothes,  utensils,  and  hands  should 
be  done  as  for  cholera.  After  an  attack  persons  may  be  carriers 
and  disinfection  of  stools  should  not  cease  upon  clinical 
recovery  but  upon  clearance  by  laboratory  examination  of 
the  feces. 

The  blood  acquires  some  resistance  to  dysentery  bacilli 
during  an  attack,  comparable  closely  to  the  changes  in 
cholera,  that  is  bacteriolytic  substances  and  agglutinins  are 
to  be  found.  Advantage  of  this  is  taken  in  immunizing  the 
lower  animals  with  toxins  obtained  in  laboratory  cultures. 
In  order  to  discover  if  dysentery  bacilli  be  present,  laboratory 


BACILLUS  DYSENTERIC  129 

cultivation  of  the  stools  is  undertaken,  using  as  material  the 
bloody  parts,  mucus  or  shreds  of  membrane,  in  any  and  all 
of  which  the  germs  abound.  The  development  in  the  labora- 
tory is  comparatively  simple,  but  to  identify  the  species  or 
variety  is  anything  but  easy.  The  agglutinins  in  the  patient's 
blood  may  be  tested  against  pure  laboratory  cultures  of 
known  varieties,  and  thus  a  bacteriological  diagnosis  as  to 
the  type  may  be  made.  Thus,  for  diagnosticating  dysentery 
we  have  only  the  feces  culture  and  agglutination  test.  Since 
the  bacilli  are  not  in  tjie  blood,  cultures  of  this  are  not  made. 

The  dysentery  bacillus  is  a  short,  straight,  non-motile  rod 
with  rounded  ends.  It  is  quite  like  the  typhoid  bacillus  in 
shape  and  size,  but  unlike  this  germ,  does  not  move  actively. 
It  may  at  times  show  degenerated  forms.  It  is  usually  single, 
but  may  be  in  pairs.  It  stains  easily.  It  grows  both  ae'ro- 
bically  and  anaerobically,  but  better  under  the  former  con- 
ditions. Its  growth  upon  laboratory  media  is  also  like  that 
of  the  typhoid  bacillus.  Best  development  occurs  at  37°  C. 
or  98°  F.,  and  death  results  when  60°  C.  or  142°  F.  is  held  for 
ten  minutes. 

It  resists  freezing  for  a  long  time,  possibly  some  weeks. 
It  is  killed  by  drying  only  after  long  periods.  Its  resistance 
to  chemicals  is  practically  the  same  as  that  of  typhoid  bacilli. 
Animals  do  not  contract  dysentery  when  they  take  the  bacilli 
by  mouth,  but  when  germs  or  their  toxins  are  introduced 
under  the  skin,  into  the  vein  or  peritoneum,  profound  intoxi- 
cation occurs,  with  fall  of  temperature,  peritonitis,  diarrhea, 
and  in  some  cases  hemorrhage  in  organs  or  body  cavities. 

Dysentery  Antiserum. — Nevertheless,  animals,  notably 
rabbits  and  horses,  have  been  made  to  withstand  large  doses 
by  preparation  with  graded  amounts.  They  develop  sera 
containing  antisubstances  to  both  the  endo-  and  extracellular 
dysentery  toxins.  This  serum  has  been  used  therapeutically 
in  the  treatment  of  dysentery  of  the  tropical  variety,  but  it 
has  not  been  found  useful  in  other  cases;  it  is  made  only 
against  what  is  called  the  Shiga  type  of  dysentery  bacillus. 
9 


L30       THE    ACUTE    SELF-LIMITED    INFECTIONS 

The  antiserum  may  also  be  used  as  a  preventive,  given  sub- 
cutaneously  in  generous  doses,  particularly  in  times  of  epi- 
demic. Our  knowledge  is  incomplete  as  to  its  full  value,  but 
the  reports  so  far  are  promising.  Vaccines  of  dead  dysentery 
bacilli  have  been  found  to  produce  a  fairly  high  grade  of 
immunity  but  give  such  sharp  reactions,  for  the  reason  given 
above,  that  their  use  has  not  become  general.  In  times  of 
epidemic  their  use  might  be  indicated  but  the  disease  can  be 
combated  by  general  hygienic  measures. 

VINCENT'S  ANGINA. 

Vincent's  angina  is  a  very  important  inflammatory  disease 
of  the  tonsils  and  pharynx,  sometimes  simulating  diphtheria 
in  that  a  false  membrane  is  also  characteristic  of  the  disease. 
The  causative  bacteria  are  spirilla  and  fusiform  rods,  prob- 


Fio.  40. — Vincent's  bacillus  with  accompanying  spirochetse.     (Park.) 

ably  two  stages  of  development  of  the  same  organism,  since 
it  is  believed  that  the  former  develop  from  the  latter.  The 
early  stage  is  the  time  when  the  pseudomembrane  appears, 
but  this  soon  gives  place  to  punched-out  ulcerations.  The 


CONJUNCTIVITIS  131 

disease  is  mild,  producing  only  a  little  local  pain,  slight  fever, 
and  malaise.  The  disease  may  coexist  with  diphtheria,  aggra- 
vating the  latter.  The  bacteria  gain  admission  by  direct 
transfer  from  a  patient  to  the  unaffected  throat.  The  con- 
dition is  not  very  contagious.  Disinfection  should  be  ob- 
served by  frequent  cleansing  of  throat  and  mouth  by  mild 
antiseptics.  Rinse  water  and  cloths  used  to  wipe  the  mouth 
may  be  rendered  innocuous  by  any  practical  disinfectant 
working  for  half  an  hour.  Little  is  known  of  the  method  of 
action  of  the  bacteria.  They  probably  produce  the  condition 
by  soluble  poisons.  In  diagnosticating  Vincent's  angina  a 
smear  from  the  false  membrane  stained  with  particular  care 
will  show  long  fusiform  rods  with  sharp  ends,  taking  the  dye 
more  deeply  at  the  ends  and  in  the  form  of  transverse  bands, 
and  quite  long,  wavy,  spiral  organisms,  usually  having 
shallow,  irregular  curvatures.  The  bacilli  are  ^yoT  to 


inch  long  and  2oooo  to  30Q00  inch  wide.  They  probably 
grow  best  under  anaerobic  conditions.  There  is  no  specific 
treatment. 

CONJUNCTIVITIS. 

There  are  many  bacteria  capable  of  producing  inflamma- 
tions of  the  conjunctival  sac,  but  there  are  a  few  that  seem 
peculiar  in  being  found  only  in  this  place.  Whether  they  are 
separate  species  or  not  remains  to  be  seen.  The  most  impor- 
tant mild  inflammation  of  the  conjunctiva  is  the  "pink 
eye."  This  acute  condition  is  transmitted  by  direct  or 
indirect  passage  of  moist  infective  material  from  one  patient 
to  another.  Therefore  an  affected  eye  should  be  kept  covered 
and  dressings  handled  carefully  The  organisms  are  killed 
by  very  weak  solutions  of  the  ordinary  disinfectants,  and, 
indeed,  probably  do  not  resist  boric  acid  very  long.  The 
causative  germ  is  the  Koch-  Weeks  bacillus  of  conjunctivitis. 
It  is  similar  in  size,  shape,  and  staining  properties  to  the 
influenza  bacillus,  but  differs  from  it  in  that  it  will  grow  in 
the  absence  of  hemoglobin,  and  with  reasonable  ease  on 


132       THE    ACUTE    SELF-LIMITED    INFECTIONS 

ordinary  culture  media.  It  is  destroyed  at  60°  C.  or  142°  F. 
in  two  minutes.  It  does  not  affect  animals.  There  is  no 
specific  therapy. 

Another  form  of  conjunctivitis  chiefly  affecting  the  angles 
of  both  eyes  and  running  a  subacute  course  is  caused  by  the 
bacillus  of  Morax  and  Axenfeld.  These  organisms  as  seen  in 
smears  made  best  from  exudate  collecting  overnight,  appear 
as  short,  end-to-end,  ovoid  rods,  each  about  12500  inch 
long.  They  may  be  cultivated  at  body  temperature  on  media 
containing  blood  or  blood  serum.  They  produce  disease  by 
their  presence  and  by  some  form  of  toxin  little  understood. 
The  disease  does  not  affect  animals. 


FIG.  41. — Koch- Weeks  bacillus  (pink-eye),  third  generation.      X  1000 
diameters.     (Weeks.) 


Trachoma. — This  is  a  subacute  and  chronic  inflammation 
of  the  conjunctiva  characterized  by  lumpy  elevations  on  the 
under  surfaces  of  the  lids  leading  to  thickening  and  distortion 
and  to  opacity  of  the  bulbar  layer.  It  has  been  variously 
ascribed  to  protozoa,  filterable  viruses,  and  bacilli  similar  to 
B.  influenza.  It  is  communicable  directly  or  by  objects 
freshly  soiled  with  secretion  from  the  eye  or  nose;  all  of 
these  should  be  disinfected. 


PERTUSSIS  OR  WHOOPING-COUGH  133 

PERTUSSIS  OR  WHOOPING-COUGH. 

This  easily  communicable  disease  is  caused  by  the  bacillus 
of  Bordet  and  Gengou,  a  congener  of  the  influenza  organism. 
Although  the  discoverers  failed  to  produce  the  typical  disease 
in  monkeys  when  using  this  bacillus,  nevertheless  they  hold 
that  the  presence  of  agglutinin  and  a  refined  blood  reaction, 
called  complement-deviation,  in  the  blood  of  patients  are 
sufficient  to  convict  it  of  being  the  cause  of  whooping-cough. 
They  assert  that  endotoxins  are  formed.  By  making  sections 
of  the  larynx  and  trachea  these  rods  have  been  found  lying 
between  the  delicate  cilia  on  the  free  surface  of  the  mucous 
membrane.  It  is  supposed  that  they  impede  the  action  of 
these  cilia  and  that  efforts  to  dislodge  them  form  the  basis 
of  the  whooping  paroxysm.  The  disease  is  transferred 
directly  from  one  patient  to  another  by  means  of  spray  from 
coughing,  spitting,  or  talking.  The  rod  grows  only  at  body 
temperature  in  the  presence  of  blood  or  its  coloring  matter. 
It  is  very  like  the  Bacillus  influenzce  in  size  and  shape.  It 
is  found  in  the  sputum  early  in  the  disease  as  a  small  ovoid 
polar  staining  rod,  arranged  in  pairs  end  to  end.  It  is  stained 
easily.  It  does  not  produce  the  disease  in  animals.  Sputum 
should  be  received  in  5  per  cent,  carbolic  acid,  and  cloths 
used  to  wipe  the  mouth  should  be  soaked  in  the  same  solution. 

No  antiserum  of  any  value  has  been  devised,  but  some 
observers  report  encouragingly  upon  vaccine  treatment  and 
prophylaxis. 


CHAPTER  X. 
THE  MORE  CHRONIC  INFECTIOUS  DISEASES. 

THE  diseases  which  have  been  discussed  are  the  most 
important  acute  infectious  diseases,  and  now  those  which  are 
accustomed  to  follow  a  more  prolonged  course  must  be  con- 
sidered. It  should  be  emphasized,  however,  that  any  one  of 
these  may  assume  a  rapid  or  fulminating  character  and  run 
its  course  quite  as  rapidly  as  the  acute  infections.  These 
chronic  infections,  particularly  tuberculosis  and  syphilis,  are 
perhaps  the  most  widespread  of  diseases. 

BACTERIUM  TUBERCULOSIS. 

Tuberculosis  is  an  infectious  disease  capable  of  attacking 
any  organ  or  structure  in  the  body,  although  its  commonest 
site  is  the  lung.  The  organism  is  the  Bacterium  tuberculosis 
or  tubercle  bacillus.  The  organism  enters  the  body  chiefly 
through  the  mouth  and  nose,  usually  by  the  air,  but  also  in 
food  and  drink.  If  it  follow  the  air  passages  it  may  settle 
upon  the  nasal,  buccal,  pharyngeal,  laryngeal,  or  bronchial 
mucous  membranes.  These  it  penetrates,  and  settles  usually 
where  there  is  lymph  tissue.  This  it  follows  with  the  lymph 
flow,  and  finds  lodgment  at  some  point  of  low  resistance. 
It  may  penetrate  to  the  true  lung  tissue  with  the  air  current, 
but  it  probably  settles  in  some  of  the  smaller  air  tubes,  and 
extends  into  adjoining  lung  tissue  by  continuity.  It  may 
enter  the  lungs  by  following  the  lymph  way,  or  it  may  get 
there  from  the  blood  stream  or  lymph  when  it  has  been  taken 
into  the  intestines  in  food  or  drink.  These  bacteria  can  pass 
through  a  mucous  membrane  into  the  deeper  tissue  without 
(134) 


BACTERIUM  TUBERCULOSIS  135 

leaving  any  inflammation  at  their  point  of  entry.  After 
having  entered  the  tissues  proper  they  may  be  carried  any- 
where by  the  lymph  and  probably  by  the  blood. 

Tubercles. — Having  settled  at  a  point  of  low  resistance, 
they  irritate  tha  tissue  rather  slowly  to  produce  a  localized 
inflammation  which  is  called  a  tubercle,  a  gray  body  about 
the  size  of  a  millet  seed.  The  cells  composing  this  little  mass 
are  very  much  the  same  as  those  seen  in  chronic  local  non- 
tuberculous  inflammations,  but  their  arrangement,  partic- 
ularly when  combined  with  large  cells  having  numerous 
nuclei  about  their  edge  (giant  cells),  is  rather  characteristic 
of  the  disease.  Many  of  these  tubercles  spread  centrifugally 
and  coalesce.  The  center  of  the  tubercles,  being  devoid  of 
nutriment,  since  the  blood  supply  is  cut  off,  undergoes  cheese- 
like  or  caseous  softening.  The  combination  of  many  tubercles 
and  their  destroyed  center  produces  large  caseous  abscesses. 
When  these  are  in  the  lungs  the  softened  centers  may  be 
removed  by  being  coughed  up  after  the  process  has  ulcerated 
into  an  air  passage.  In  the  kidney  the  same  general  thing 
may  occur,  and  the  softened  matter  goes  into  the  urine. 

Forms  of  Tuberculosis. — When  the  process  ulcerates  into 
the  blood  supply  there  may  result  a  rapid  dissemination  of  the 
bacteria  throughout  the  body,  with  the  production  of  innu- 
merable miliary  tubercles  everywhere.  Among  the  special 
forms  of  tuberculosis  are  meningitis,  hip  disease,  and  spine 
(Pott's)  disease.  The  first  is  a  long-standing  inflammation  in 
which  the  coverings  of  the  brain  and  cord  and  the  superficial 
layers  of  these  organs  are  involved  in  an  extensive  inflamma- 
tion. The  hip  and  spine  diseases  arise  when  the  bacteria  get 
into  the  soft  marrow  of  the  bones,  and  extend  to  the  joint 
and  tissues  about  it. 

Toxins. — The  peculiar  evidences  of  tuberculosis  are  due  to 
the  toxins  elaborated  by  the  causative  germ,  which  are  both 
extracellular  and  endotoxic.  The  former  produce  the  con- 
stitutional symptoms  of  fever  and  general  depression  of 
health.  They  are  also  probably  responsible  for  some  of  the 


136     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

inflammation  in  the  neighborhood  of  tubercles.  The  endo- 
toxins,  on  the  other  hand,  produce  the  peculiar  local  inflam- 
mation called  the  tubercle,  and  cause  its  degeneration  into 
caseous  material.  During  an  infection  with  tuberculosis 
there  will  be  developed  in  the  body  fluids  a  very  slight 
amount  of  substances  as  antibody  to  these  endo-  and  extra- 
cellular poisons.  It  is  of  little  importance  in  the  diagnosis, 


FIG.  42. — Tuberculosis  of  the  lung.     (Stengel.) 

treatment,  or  protection  of  the  individual,  and  a  specific 
resistance  to  tuberculosis  is  not  acquired  by  passing  through 
an  attack.  Recovery  ensues  when  the  health  of  the  individual 
and  his  tissues  is  strong  enough  to  inhibit  the  multiplication 
of  bacilli.  A  lighting  up  of  the  disease  may  occur  when  the 
resistance  weakens  by  reason  of  some  acute  disease,  bad 
habits  and  the  like. 


PLATE  VI 


/  ^   \  •  J^/ 


^ 


Tuberculous  Sputum.     (Abbott.) 


BACTERIUM  TUBERCULOSIS  137 

Predisposing  Causes  and  Transmission. — Tuberculosis  spares 
no  walk  of  life,  but  is  more  common  when  the  lack  of  body 
care  reduces  resistance.  It  is  preeminently  the  disease  of 
crowded,  dark,  illy  ventilated,  badly  drained  tenements.  It 
comes  in  the  pulmonary  form  frequently,  as  an  infection  on 
top  of  an  acute  cold.  The  disease  is  spread  in  by  far  the 
largest  percentage  of  cases  by  the  direct  inhalation  of  germs 
coughed  out  by  a  tuberculous  person  and  contained  in  dust 
contaminated  by  tuberculous  sputum.  The  sputum  must, 
of  course,  dry  before  it  is  pulverized  into  dust  by  walking  on  it 
or  sweeping  it.  The  dust  arising  from  soiled  handkerchiefs 
or  cloths  is  likewise  a  danger.  Park  says  that  as  many  as 
5,000,000,000  tubercle  bacilli  may  be  expectorated  by  a  con- 
sumptive person  in  twenty-four  hours.  Since  the  ordinary 
uneducated  consumptive  is  very  careless  of  his  expectoration 
the  danger  is  obvious.  The  great  movement  against  the 
"  white  plague,"  now  active  throughout  the  world,  is  rapidly 
correcting  the  habits  of  careless  patients. 

Tuberculosis  may  also  be  transmitted  by  the  infection  of 
food  in  the  soiled  hands  of  patients,  or  flies  may  feed  upon 
sputum  and  carry  the  germs  upon  their  body.  The  study  of 
the  transmission  of  tuberculosis  from  the  cow  to  the  human 
being  has  now  progressed  to  a  point  near  solution.  Koch 
said  that  the  bovine  bacillus  is  not  infective  for  the  human 
being.  This  may  be  true  for  tuberculosis  of  the  lungs,  but 
children  are  susceptible  to  the  bovine  form,  which  can  pro- 
duce in  them  tuberculosis  of  the  glands  of  the  neck  and 
abdominal  cavity,  and  of  the  meninges.  Cows  may  give  off 
tubercle  bacilli  in  their  milk  even  when  there  is  very  slight 
evidence  of  the  disease  in  their  body.  Milk,  unless  it  is  known 
to  come  from  a  non-tuberculous  cow,  should  not  be  used. 

The  tubercle  bacillus  may  be  eliminated  from  the  human 
body  by  the  feces,  and  health  authorities  are  requiring  the 
disinfection  of  sewage  from  sanatoria.  Tuberculosis  is  very 
rarely  hereditary,  but  children  born  of  tuberculous  parents 
are  not  quite  as  robust  as  children  born  of  non-tuberculous 


138      THE   MORE   CHRONIC  INFECTIOUS   DISEASES 

persons,  and  therefore  they  more  easily  contract  the  disease 
from  the  surroundings  contaminated  by  ill  parents. 

Disinfection. — To  disinfect  material  from  the  tuberculous 
individual  it  is  necessary  to  collect  it  in  some  manner, 
permitting  burning  or  the  action  of  chemicals  over  a  long 
time.  Tuberculous  sputum  is  best  received  in  cardboard 
boxes  enclosed  in  a  tin  cup.  The  boxes  are  burned,  and 
the  tin  cup  washed  in  5  per  cent,  carbolic  acid  at  frequent 
intervals.  If  the  person  expectorate  into  cloths  they  should 
be  burned  or  soaked  in  5  per  cent,  carbolic  acid  for  at 
least  six  hours.  If  neither  of  these  methods  is  used  ex- 
pectoration should  be  received  in  a  bowl  or  pot  contain- 
ing 5  per  cent,  carbolic  acid  or  lime  solution;  the  latter  is 
a  cheap,  simple  and  very  efficacious  disinfectant  for  all 
tuberculous  matter.  Feces  and  urine  should  be  received  and 
well  mixed  into  the  same  solutions.  After  death  from  tuber- 
culosis the  room  and  all  contents  should  be  disinfected  with 
formaldehyde  gas. 

Diagnosis. — The  most  important  means  of  diagnosis  is 
by  finding  the  tubercle  bacillus.  To  do  this,  the  sputum 
urine,  feces,  pus,  exudate,  or  a  piece  of  tissue  is  taken,  stained 
by  special  methods,  or  injected  into  guinea-pigs.  The 
material  to  be  examined  is  spread  on  glass  slides  and  stained 
by  a  special  technic.  The  tubercle  bacillus,  because  of  the 
presence  of  waxy  and  fatty  matters  in  it,  stains  with  difficulty 
and  when  once  stained  cannot  be  decolorized  by  acid  or 
alcohol,  for  this  reason  being  called  an  acid-fast  organism. 
In  order  to  stain  the  rod  it  is  customary  to  use  a  chemical, 
called  a  mordant,  to  assist  the  staining  material  in  pene- 
trating; these  mordants  are  usually  carbolic  acid  and  anilin 
oil.  The  dye  is  usually  fuchsin,  imparting  a  red  color  to  the 
organisms.  After  staining,  a  decolorizing  solution  is  applied 
to  the  preparation  and  all  but  the  tubercle  bacilli  are  de- 
stained,  leaving  red  bacilli,  which  are  easily  distinguished 
under  the  microscope. 

Sometimes  the  germs  are  present,  but  cannot  be  found  by 


BACTERIUM  TUBERCULOSIS  139 

staining.  Some  of  the  material  is  then  introduced  under  the 
skin  or  into  the  peritoneal  cavity  of  guinea-pigs.  If  tubercle 
bacilli  be  present,  evidences  of  the  disease  will  appear  in  these 
animals  in  from  two  to  five  weeks.  The  bacilli  can  be  found 
by  staining  smears  from  the  tubercles.  Agglutinins  are 
formed  in  tuberculosis,  but  the  clumping  test  is  of  little 
value. 

The  tuberculin  reaction  is  a  very  important  diagnostic 
measure.  During  its  growth  on  artificial  media  in  the 
laboratory,  the  tubercle  bacillus  develops  its  endo-  and 
extracellular  toxins.  If  these  poisons,  called  "tuberculin," 
obtained  by  removing  the  living  organisms  from  a  fluid 
culture,  be  injected  under  or  rubbed  into  the  skin,  a  char- 
acteristic reaction  occurs.  The  subcutaneous  injection  of  as 
small  a  quantity  as  5  milligrams  or  about  YG  minim  of 
Koch's  tuberculin  will  cause  a  definite  rise  of  temperature 
and  a  feeling  of  general  malaise  within  twenty-four  hours. 
There  is  besides  this  a  congestion  of  the  tuberculous  process 
in  the  lung  or  wherever  it  may  be.  The  inunction  of  a  drop 
of  this  solution  into  the  skin,  combined  with  a  slight  irritation 
of  the  surface,  will  cause  a  reddened  papule  or  even  a  vesicle 
upon  a  swollen  base  to  appear  within  twenty-four  hours. 
There  are  several  modifications  of  this  skin  test  in  practice, 
but  the  principle  is  the  same  in  all.  Tuberculin,  purified 
by  precipitation  with  alcohol,  can  be  obtained  in  powder 
form,  a  solution  of  which  has  the  property  of  calling  forth  a 
reaction  in  a  tuberculous  person.  This  refined  product  is 
used  in  the  conjunctival  test  by  dropping  a  small  quantity 
into  the  eye.  If  tuberculosis  be  present  a  congestion  and 
discharge  will  appear  in  the  conjunctiva  within  forty-eight 
hours. 

It  is  claimed  by  many  that  all  adults  have  some  tuber- 
culosis in  their  body,  acquired  during  childhood,  which  has 
remained  quiet  or  has  healed  completely,  but  which  has  left 
their  blood  in  such  a  condition  that  a  tuberculin  reaction  will 
appear.  For  this  reason  the  skin  test  may  be  positive  in 


140     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

adults  who  are  really  not  suffering  from  their  slight  latent 
infection,  and  it  is  therefore  not  reliable.  It  should  only  be 
used  in  children.  The  supposed  cause  of  the  tuberculin  test 
.either  under  or  upon  the  skin,  is  the  stimulation  of  the  tuber- 
culous disease  by  the  introduced  toxin,  and  the  outpouring 
from  the  tubercles  of  more  of  their  own  poison.  No  reaction 
of  any  sort  follows  the  administration  of  tuberculin  to  persons 
free  from  tuberculosis. 

Morphology  and  General  Characteristics. — The  tubercle 
bacillus  is  a  true  parasite,  that  is,  it  does  not  multiply  in  nature 
outside  the  animal  body.  It  is  a  rather  large  organism,  about 

70000    incn    wide   and   fr°m    20000    to    5~oVo    incn    long-       Jt 

may  be  straight  or  slightly  bent,  usually  single,  but  also  in 
pairs.  It  is  non-motile,  and  produces  no  spores.  It  stains 
with  considerable  difficulty,  owing  to  its  thick  cell  wall. 
There  is  much  fatty  and  waxy  matter  in  the  tubercle  bacillus 
which  gives  it  its  resistant  power.  It  grows  upon  laboratory 
culture  media  very  slowly.  For  this  reason  it  must  be 
obtained  in  as  pure  a  condition  as  possible.  Cultures  are  best 
made  from  the  lesions  in  guinea-pigs.  For  its  growth  this 
organism  requires  the  addition  of  glycerin,  blood  serum,  or 
egg  to  the  ordinary  nutrient  broths  and  jellies.  It  will  grow 
only  at  body  temperature,  and  not  at  room  temperature. 

It  is  killed  by  an  exposure  to  60°  C.  or  142°  F.  in  thirty 
minutes,  to  70°  C.  or  160°  F.  in  ten  minutes,  and  at  95°  C.  or 
200°  F.  in  one  minute  in  watery  suspension.  Dry  heat  at 
100°  C.  or  212°  F.  requires  about  one  hour.  The  organisms 
resist  drying  in  the  dark  for  considerable  periods.  Direct 
sunlight  kills  them  if  in  thin  layer  or  small  clumps  within  four 
hours.  Diffused  light  requires  two  weeks  for  their  destruc- 
tion. Sputum  protected  from  direct  sunlight  may  contain 
living  bacilli  possibly  for  one  year.  Five  per  cent,  carbolic 
acid  should  certainly  kill  them  in  sputum  in  twelve  hours; 
in  watery  suspension  in  thirty  minutes.  Bichloride  of  mercury 
is  not  of  value  for  sputum  disinfection,  but  in  strength  of  1  to 
1000  in  watery  suspension  is  fatal  in  one  hour.  No  kind  of 


BACTERIUM  TUBERCULOSIS  141 

animal  is  absolutely  resistant  to  tuberculosis,  but  there  are 
some  that  very  seldom  present  the  spontaneous  disease, 
notably  dogs  and  horses. 

There  are  four  forms  of  varieties  of  the  tubercle  bacillus: 
the  human,  bovine  or  cow,  bird,  and  reptilian.  The  first  two 
only  concern  us,  and  the  distinguishing  features  of  these 
groups  are  of  small  importance  here.  The  infectiousness  of 
the  bovine  form  for  humans  has  been  mentioned.  The 
human  form  is  of  very  low  virulence  for  the  cow,  but  may 
infect  most  of  the  smaller  animals.  It  has  been  found  impos- 
sible to  obtain  from  any  of  the  lower  animals  a  serum  which 
will  have  a  beneficial  effect  upon  the  disease  in  human 
beings,  that  is,  no  serum  can  be  procured  which  will  give  a 
passive  immunity. 

Tuberculin. — The  poisons  made  in  cultures  and  used  for  the 
tuberculin  test  in  the  form  of  Koch's  tuberculin  have  already 
been  mentioned.  There  are  many  forms  of  tuberculin  which 
are  incidentally  modelled  after  Koch's  plans.  His  original 
was  a  broth  upon  which  the  bacteria  had  grown,  but  free 
of  living  forms  and  reduced  by  evaporation  to  one-tenth  its 
original  volume.  This  contained  both  the  endo-  and  extra- 
cellular toxins.  His  later  forms  consisted  of  killed  bacteria, 
of  a  watery  extract  from  them  and  lastly,  living  bacteria  so 
reduced  in  virulence  that  they  could  not  produce  tuberculosis. 
These  are  all  tuberculins,  the  last  forms  being  called  vaccines 
also.  Not  only  are  these  toxic  solutions  of  value  for  diag- 
nosticating tuberculosis,  but  they  may  also  be  used  in  treat- 
ment, the  purpose  being  to  induce  some  active  immunity  to 
the  tubercle  bacillus  poisons.  They  are  injected  under  the 
skin  of  tuberculous  patients,  beginning  with  extremely  minute 
doses,  too  small  to  produce  the  tuberculin  reaction  described 
abo\e.  We  increase  the  quantity  gradually  until  the  patient 
can  endure  large  amounts.  It  is  maintained  that  this  treat- 
ment is  very  beneficial  and  that  a  slight  immunity  is  achieved. 
Opinions  vary  as  to  its  value,  but  those  who  have  had  longest 
experience  usually  testify  to  its  efficacy,  although  no  one 


142     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

maintains  that  it  is  a  cure-all,  but  merely  another  means  of 
treating  this  serious  disease.  This  is  in  reality  an  active 
immunization  during  the  course  of  the  disease,  but  it  has  not 
been  found  possible  to  inject  a  healthy  person  in  the  same 
manner  and  thereby  increase  his  resistance  to  tuberculosis 

TREPONEMA  PALLIDUM. 

Syphilis  is  one  of  the  venereal  diseases.  It  is  chiefly 
acquired  by  cohabitation,  but  may  also  be  contracted  by 
nurses  and  physicians  in  their  professional  relations  with 
patients.  It  is  a  chronic  infectious  disease  characterized  by 
three  stages,  the  first  a  primary,  acute,  active,  self-limited 
ulceration,  with  some  regional  lymph-gland  swellings; 
second,  a  period  in  which  various  eruptions  appear  on  the 
skin  and  mucous  membranes  (mucous  patches)  with  slowly 
progressive  changes  in  some  of  the  internal  organs,  and  third, 
a  last  stage  of  soft  tumor  formation  (gumma),  with  fibrous 
affections  of  the  organs  and  degenerations  of  the  nervous 
system. 

It  is  caused  by  a  spiral  organism  called  the  Spirocheta 
pallida  or  Treponema  pallidum.  This  microbe  enters  small 
cracks  or  wounds,  penetrates  to  the  deeper  layers,  invades 
the  lymph  channels,  and  produces  the  primary  sore,  the 
hard  chancre.  Even  before  this  is  fully  developed,  the  spiro- 
chetse  have  journeyed  to  the  neighboring  lymph  glands, 
where  an  enlargement  results.  They  then  invade  both  the 
lymph  routes  and  the  blood  and  rapidly  infest  all  bodily 
tissues.  They  stimulate  the  small  round  cells  of  blood  and 
tissue  to  multiply  even  up  to  fibrous  tissue  formation,  and 
they  cause  degeneration  of  the  functionating  structures. 
Just  how  they  make  the  gumma  is  only  conjectured.  All 
their  effects,  however,  are  probably  due  to  the  toxins  set 
free  upon  their  death  and  disintegration.  The  spirochetse 
remain  in  the  body  as  long  as  the  patient  lives,  if  untreated. 
They  leave  the  patient  probably  only  with  the  moisture  of 


TREPONEMA  PALLIDUM  143 

ulcerated  surfaces,  and  one  protects  against  contamination 
by  covering  the  ulcerated  surfaces  or  wearing  hand  protec- 
tion. The  mildest  of  antiseptics  will  destroy  the  germs. 
The  incubation  period  varies  from  four  weeks  to  as  many 
months. 

Forms  of  Syphilis. — This  frightful  disease  which  causes  so 
much  mental  and  physical  suffering  may  be  hereditary, 
congenital,  or  acquired.  The  course  of  the  three  types 
varies  a  little,  but  the  ultimate  effect  is  the  same  in  all.  In 
the  first  there  are  evidences  of  imperfect  physical  and  mental 
development;  the  second  is  an  active  form  of  the  disease  with 
symptoms  and  infectious  catarrhs  and  is  easily  transmitted 
to  attendants;  the  third  is  the  form  described  above. 

Transmission. — Aside  from  cohabitation,  syphilis  may  be 
transmitted  by  kissing,  examining  a  patient,  or  using  any 
object  that  has  come  in  contact  with  an  open  sore.  Wet- 
nurses  may  contract  it  from  infected  children  and  transmit 
it  to  healthy  children  whom  they  nurse.  Both  may  be  pro- 
tected if  those  in  charge  will  have  a  Wassermann  test  made. 
If  the  child  be  syphilitic  it  should  be  raised  on  the  bottle, 
while  a  wet-nurse  with  the  disease  would  better  never  nurse 
other  than  her  own  child.  In  protecting  against  infection 
a  weak  (1  to  2000)  bichloride  of  mercury  solution  should 
always  be  on  hand  that  the  ulcers  may  be  wiped  before 
examination  and  the  hands  disinfected  afterward.  That 
occupying  a  bed  with  an  actively  diseased  syphilitic  or  using 
anything  belonging  to  such  a  person  must  be  avoided  goes 
without  saying. 

Diagnosis. — In  the  serum  of  a  syphilitic  certain  anti- 
bodies are  formed  that  can  be  made  use  of  in  diagnosis. 
This  is  the  basis  of  the  Wassermann  test  upon  the  blood, 
due  to  antibodies  like  bacteriolysis.  Its  theory  and  practice 
are  too  intricately  technical  to  be  included  here.  Suffice 
it  to  say  that  it  is  certainly  a  positive  test  in  95  per  cent,  of 
cases  in  which  there  exists  untreated  syphilis.  Proper  treat- 
ment destrovs  the  Wassermann  reaction,  but  whenever  it 


144     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

results  positively  some  form  of  syphilis  is  present,  although 
it  may  not  be  in  a  form  transmissible  to  others.  Otherwise 
syphilis  is  diagnosticated  by  finding  spirochetes  in  the  serum 
which  exudes  from  chancres,  skin  eruptions,  and  mucous 
patches,  or  the  venereal  warts  on  mucous  membranes.  This 
serum  is  taken  and  looked  at  unstained  upon  a  background 
of  India  ink  or  by  what  is  called  dark-field  illumination,  a 
process  by  which  the  light  is  made  to  shine  upon  the  body 
of  the  spiral  from  the  side.  It  can  also  be  stained  by  appro- 
priate methods,  but  its  minute  size  and  paleness  make  this  a 
trying  test. 


FIG.  43. — Treponema  pallidum  appearing  as  bright  refractive  body  on  a 
dark  field,  as  shown  by  India  ink  or  ultramicroscope.     (Park.) 

Morphology  and  General  Characteristics. — The  Spirocheta 
pallida  is  a  corkscrew-like,  actively  motile,  delicate  thread.  Its 
windings  assume  the  form  of  a  large  arc  of  a  small  circle,  and 
vary  from  four  to  twenty.  It  is  1 0 o^ o o  to  75000" incn  wide 
and  from  gWo  to  Woo  inch  lonS-  It;  moves  by  end  flagella, 
in  a  screwing  and  waving  motion.  It  is  killed  rapidly  by 
drying,  a  very  fortunate  thing,  as  many  people  are  thereby 


TREPONEMA  PALLIDUM  145 

protected.  Against  weak  bichloride  and  carbolic  acid  it  has 
no  resistance.  Alcohol  will  destroy  it  in  five  minutes.  Up 
until  the  beginning  of  1911  no  success  had  met  attempts  to 
cultivate  these  spirals  in  the  laboratory.  Noguchi  finally 
succeeded  in  growing  them  under  anaerobic  conditions  in  a 
mixture  of  serum  and  agar  to  which  a  piece  of  sterile  liver  or 
kidney  of  rabbit  had  been  added.  Only  rabbits  and  monkeys 
among  the  lower  animals  can  be  made  to  contract  syphilis, 
but  of  these  only  the  latter  shows  any  similarity  to  man  in  the 
course  of  the  disease.  When  infective  crusts  from  eruptions 
or  serum  exuding  from  them  is  kept  in  the  test-tube  for  six 
hours,  infection  can  no  longer  be  transferred  to  monkeys. 
No  serum  of  therapeutic  value  has  as  yet  been  produced,  nor 
can  immunity  be  induced  by  injecting  dead  spirochetes.  A 
remedy,  salvarsan,  consisting  of  a  complex  arsenical  com- 
pound, has  been  found  to  cure  syphilis.  It  is  efficacious  at  all 
stages,  stopping  and  curing  the  disease  if  given  at  the  time 
of  chancre,  and  materially  improving  the  nervous  condition 
of  the  late  stages.  Lately,  Noguchi  has  made  an  extract  of 
spirochete  bodies  which  can  be  used  as  a  skin  test  for  syphilis 
precisely  as  tuberculin  is  rubbed  into  the  skin  in  diagnosis 
of  tuberculosis.  He  claims  good  results  during  the  later 
stages,  but  as  a  diagnostic  test  of  recent  infection  it  has  not 
yet  proved  of  value. 

Chancroid. — There  is  a  venereal  disease  known  as  chancroid 
or  soft  chancre  in  contradistinction  to  the  primary  hard 
chancre  of  syphilis.  This  is  an  acute  infectious  condition  due 
to  the  bacillus  of  Ducrey.  The  lesion  begins  as  a  pustule, 
which  soon  breaks  down  into  a  spreading  ulcer.  The  disease 
is  communicated  by  direct  contact  usually.  The  bacilli  are 
in  the  discharges  and  therefore  can  be  transferred  through 
the  intervention  of  dressings.  The  bacilli  are  extremely 
small,  double  rods,  not  motile,  and  form  no  spores.  They 
grow  on  laboratory  media  containing  blood.  They  do  not 
possess  a  great  viability  under  artificial  conditions,  and  there- 
fore are  destroyed  in  discharges  quite  easily.  Simple  drying 
10 


146     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

seems  to  kill  them  shortly,  and  weak  solutions  of  the  ordinary 
disinfectants  are  quickly  efficient.  We  assist  in  the  clinical 
diagnosis  of  chancroid  by  finding  the  diplo-rods,  mostly 
within  leukocytes,  in  scrapings  from  the  depth  of  the 
ulceration. 

RELAPSING  FEVER. 

Relapsing  fever  is  caused  by  spirochetes  whose  species 
differ  in  the  various  countries,  Europe,  Africa,  India,  and 
America.  The  transmission  is  only  known  for  the  African 
variety,  which  spreads  by  mea,ns  of  a  tick.  The  spirochete 


FIG.  44. — Spirocheta  o  bermeieri  blood  smear.     Fuchsin.      X  1000 
diameters.     (From  Itzerott  and  Neimann.) 

circulates  in  the  blood  during  attacks  and  settles  in  the  spleen 
between  them.  The  disease  is  characterized  by  intermittent 
attacks  of  continued  fever  beginning  suddenly,  lasting  four 
to  six  days,  and  ending  by  crisis.  The  febrile  periods  recur 
with  eight  to  ten  days'  intervals  of  freedom  from  symptoms. 
Blood  is  examined  during  the  fever  and  we  find  under  the 
microscope  long,  ^oVo  incn>  delicate,  50Q00  inch  wide,  wavy 
spirals  with  corkscrew  and  undulatory  movements. 

The  spirochetes  have  been  cultivated,  under  anaerobic 
conditions,  in  serum  supplied  with  fresh  animal  tissue  and 
these  cultures  may  be  transferred  to  monkeys  and  mice. 


BACTERIUM  LEPRM  147 

Some  immunity  is  left  after  an  attack,  and  use  has  been  made 
of  the  serum  in  treating  the  sick.  As  there  are  several  species 
of  this  spirochete,  differing  very  slightly,  it  is  necessary  to 
use  many  varieties  to  make  an  antiserum. 

BACTERIUM  LEPR51. 

Leprosy  is  a  chronic  endemic  infectious  disease  charac- 
terized by  the  development,  in  the  skin  chiefly,  but  also  the 
mucous  membranes,  of  firm  nodules  and  diffuse  swellings  due 
to  the  growth  and  irritation  of  the  Bacterium  leprce  or  leprosy 
bacillus. 

Forms  of  Leprosy. — There  are  two  forms',  the  nodular  and 
anesthetic.  The  former  is  usually  painless  throughout  its 
course,  merely  giving  rise  to  the  cutaneous  nodules.  The 
anesthetic  form  is  due  to  an  involvement  of  the  sensory 
nerves,  which  are  at  first  irritated  with  the  production  of  a 
painful  .early  stage,  followed  by  destruction  of  sensation 
when  the  inflammation  has  progressed  further.  The  disease 
gives  rise  to  considerable  superficial  destruction  of  tissue, 
which  is  responsible  for  the  horrible  pictures  of  this  disease 
in  the  lay  mind.  Fingers,  toes,  nose,  and  pieces  of  skin  may 
be  removed  by  ulceration.  The  disease  is  an  old  and  wide- 
spread one,  commonest  in  the  tropics,  but  by  no  means 
confined  to  them.  Despite  long  familiarity  with  leprosy, 
there  are  many  points  as  yet  undecided  about  its  nature. 

Transmission. — The  bacteria  probably  enter  by  the  nose 
and  mouth,  and  it  requires  close  association  with  a  leper  for  a 
long  time  in  order  to  contract  the  disease.  It  seems  that  it 
may  be  hereditary  in  the  sense  that  parent  and  child  may  be 
infected.  It  is  much  more  probable  that  the  child  is  born 
free  of  disease  and  acquires  it  by  association  with  the  parent. 
The  low  contagiousness  of  leprosy  should  be  emphasized. 
If  one  should  say  in  a  crowd.  "There  is  a  leper!"  the  people 
would  shun  him  as  if  he  were  a  maniac  with  a  firearm.  If 
one  were  to  say  under  similar  conditions,  "There  is  a  con- 


148     THE  MORE  CHRONIC  INFECTIOUS   DISEASES 

sumptive!"  he  would  be  pitied  and  perhaps  not  avoided  at 
all.  Tuberculosis  is  vastly  more  easily  transmitted  than 
leprosy.  The  inhuman  treatment  accorded  to  lepers  is  due 
to  this  misapprehension. 

When  the  bacteria  enter  the  mucous  surfaces  they  are 
carried  by  the  lymph  or  blood  to  the  exposed  skin  surfaces, 
chiefly  the  face  and  hands.  Here  they  settle  in  the  subcu- 
taneous tissues  and  nerves,  producing  a  chronic  inflammation 
in  which  lepra  cells  are  found.  These  are  large  round  or  oval 


FIG.  45. — Schematic  representation  of  section  through  a  lepra  nodule: 
left  side  of  picture  gives  appearance  under  low  magnifying  power;  right 
side,  the  appearance  when  highly  magnified.  In  the  latter  the  large  lepra 
cells  are  diagrammatically  indicated.  (Abbott.) 

cells,  crowded  with  bacilli,  lying  irregularly  throughout  the 
inflammatory  tissues.  Leprosy  does  not  form  definite 
tubercles  like  tuberculosis,  but  the  process  is  more  diffuse; 
nor  does  caseation  occur.  Giant  cells  are  uncommon.  The 
bacilli  produce  these  changes  largely  by  poison  in  their 
body  and  by  mechanical  irritation.  There  is  some  reason  to 
believe,  by  most  recent  researches,  that  a  soluble  or  extra- 
cellular poison  is  formed.  The  bacteria  are  discharged  from 
the  patient  by  the  sloughing  of  wounds,  especially  the  ulcers 
in  the  nose  and  throat.  The  dressings  and  cloths  used  to 


BACTERIUM  LEPRM  149 

wipe  the  nose  should  be  burned.  Intimate  contact,  such  as 
sleeping  with  or  kissing  lepers,  should  be  avoided,  but  there 
is  no  proof  that  ordinary  relations  of  human  life  easily  trans- 
mit the  disease.  The  best  diagnosis  te  made  by  finding  the 
rods  in  their  peculiar  cells,  which  is  best  achieved  by  removing 
a  piece  of  the  skin  growths. 

Morphology  and  General  Character. — The  leprosy  bacillus, 
like  the  tubercle  bacillus,  is  stained  with  difficulty,  and 
belongs  to  what  are  called  the  acid-fast  bacteria.  Methods 
similar  to  that  described  for  the  tubercle  bacillus  must  be 
used,  but  the  determination  is  by  no  means  simple  even  to 
the  most  experienced  bacteriologists.  The  similarity  to  the 
tubercle  bacillus  is  further  shown  by  the  fact  that  the  tuber- 
culin skin  test  is  positive  in  lepers.  A  poison  similar  to  tuber- 
culin, called  leprin,  has  been  made  by  extracting  leprous 
tissue.  It  is  only  within  the  last  few  years  that  the  pure 
direct  cultivation  of  Bacterium  leprce  has  been  successful, 
and  then  only  upon  special  media  with  a  very  delicate  technic. 
More  about  the  poisons  will  probably  be  learned  in  the  near 
future.  The  bacillus  of  leprosy  is  a  straight  rod  with  rounded 
ends,  a  trifle  smaller  than  the  tubercle  bacillus.  Its  resist- 
ance to  chemicals  and  heat  is  probably  the  same  as  that 
organism.  It  grows  only  at  body  temperature.  Some 
attempts  have  been  made  to  use  devitalized  leprous  tissue 
and  the  vaccines  from  the  tubercle  bacilli  as  a  remedy. 
These  have  met  with  indifferent  success. 

Acid-fast  Bacteria. — The  two  organisms  of  tuberculosis 
and  leprosy  are  members  of  the  acid-fast  group.  There  are 
numerous  other  bacteria  that  stain  and  are  decolorized 
with  difficulty,  but  these  are  the  important  disease  producers. 
Such  an  organism,  called  the  Bacterium  smegmatis,  exists 
normally  in  the  smegma  about  the  genitals,  and  is  often  a 
source  of  confusion  when  examining  for  tuberculosis  of  the 
urogenital  apparatus.  It  does  not  produce  disease,  however. 
It  is  possible  also  to  exclude  it  by  a  special  staining  method. 
Other  acid-fast  bacteria  exist  in  manure,  hay,  and  butter. 


150     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 


BACTERIUM  MALLEI. 

Glanders  is  chiefly  a  disease  of  horses,  characterized  by 
nodular  growths  and  ulcers  in  the  upper  air  passages  or  diffuse 
swellings  under  the  skin.  In  the  latter  form  it  is  called  farcy. 
The  causative  organism  is  the  Bacterium  mallei  or  glanders 
bacillus.  Human  beings,  who  are  associated  with  horses  or 
who  work  in  the  laboratory  with  cultures,  may  contract  the 
disease,  usually,  however,  in  the  acute  form,  whereas  the 
lower  animals  commonly  have  a  protracted  attack.  The 
bacteria  enter  by  small  cracks  or  wounds  in  the  mucous 
membrane  of  the  mouth  or  nose,  and  are  carried  by  the  lymph 
or  blood  to  subcutaneous  tissues.  Whether  they  produce 
glanders  proper  or  farcy,  they  stimulate  the  tissues  to  pro- 
duce nodules  not  unlike  the  tubercle,  but  of  more  rapid 
progression.  Quite  early  they  break  down  into  abscesses  or 
through  the  skin  as  large  sloughing  ulcers.  The  poisons  are 
almost  entirely  endotoxins,  and  may  be  extracted  from  cul- 
tures. A  slight  amount  of  resistance  is -gained  by  passing 
through  an  attack. 

Diagnosis. — Agglutinins  are  found  in  the  blood  and  the 
clumping  test  is  a  valuable  means  of  diagnosis.  The  bacteria 
may  also  be  found  by  making  smears  and  cultures  from  open 
ulcers  or  by  withdrawing  some  of  the  pus  from  an  abscess. 
This  pus  may  be  injected  into  the  peritoneal  cavity  of  a 
guinea-pig,  obtaining  as  evidence  of  the  presence  of  the 
Bacterium  mallei  an  inflammation  of  the  testis.  The  most 
practical  method  of  diagnosticating  glanders  is  by  the  use  of 
the  mallein  test.  Mallein  is  the  poison  elaborated  by  the 
Bacterium  mallei  in  laboratory  cultures.  It  is  comparable 
to  tuberculin,  and  may  be  used  like  it,  by  injecting  it  under 
or  by  rubbing  it  upon  the  skin.  Reactions  of  temperature 
and  reddening  of  the  skin  indicate  the  presence  of  glanders. 
The  bacilli  may  be  found  also  in  stained  smears  of  the  pus 
lying  in  pairs  on  end  within  the  large  so-called  epithelioid 
cells.  Blood  cultures  sometimes  give  a  growth.  The  disin- 


BACTERIUM  MALLEI  151 

faction  of  human  material  should  consist  in  burning  all 
dressings  from  ulcers  or  cloths  used  to  wipe  the  nose  or  mouth. 
Bacteria  leave  the  body  only  with  the  purulent  discharges. 
Strong  antiseptics,  such  as  1  per  cent,  carbolic  acid,  should  be 
used  for  the  hands  and  objects  possibly  soiled  by  discharges. 
Glanders  is  a  very  infectious  disease,  and  the  bacilli  are  per- 
tinacious. Isolation  of  the  patient  must  be  absolute,  attend- 
ants must  wear  masks,  head  covering  and  gloves,  and  all 
forms  of  disinfection  must  be  continued  until  the  lesions  are 
declared  free  of  glanders  bacilli  by  culture.  Horses  with 
glanders  are  destroyed  and  their  stalls  thoroughly  disinfected. 


FIG.  46. — Glanders  bacilli.   Agar  culture.    X  1100  diameters.     (Park.) 

Morphology  and  General  Characteristics. — The  glanders 
bacilli  are  straight  or  slightly  curved  rods,  usually  single,  but 
also  in  pairs  or  short  filaments,  and  measure  from  2oooo  to 
soVo  mcn  in  length  and  from  1 0  ^  0  0  to  50i00  inch  in  width. 
They  stain  with  reasonable  ease.  They  grow  at  37°  C.  or 
98°  F.  very  much  better  in  the  presence  of  oxygen  than  in 
its  absence.  They  do  not  form  spores  nor  are  they  motile. 
They  are  killed  at  55°  C.  or  130°  F.  in  ten  minutes;  by  1  to 
1000  bichloride  or  1  to  100  carbolic  acid  in  ten  minutes. 


152     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

After  drying  they  may  live  for  ten  days,  but  do  not  live  long 
in  nature  outside  the  animal  body.  They  are  easily  grown 
upon  most  of  the  laboratory  foodstuffs.  Most  of  the  lower 
animals  are  susceptible  to  glanders  and  it  is  of  some  impor- 
tance in  menageries.  The  disease  in  animals  is  like  that 
described  for  persons,  and  the  beasts  do  not  develop  any- 
thing in  their  blood  which  can  be  used  to  treat  human  beings. 
Vaccines  are  not  successful  probably  because  the  disease  in 
people  is  too  acute  to  be  amenable  to  a  treatment  with 
mallein  comparable  to  that  described  for  tuberculin. 


BACTERIUM  ANTHRACIS. 

Anthrax,  or  woolsorters'  disease,  or  splenic  fever,  is  chiefly 
an  acute  infectious  disease  of  animals  caused  by  the  Bac- 
terium anihracis  or  anthrax  bacillus.  It  is  contracted  by 
human  beings  through  association  with  infected  animals, 
hides,  wool,  rags  and  the  like;  cases  have  been  known  to 
arise  from  shaving  brushes  in  which  the  bristles  were  not 
properly  sterilized.  It  is  expressed  as  superficial  abscesses, 
pustules,  or  carbuncles  scattered  over  the  skin,  or  as  softening 
of  the  spleen,  hemorrhages  into  the  intestinal  wall  and  some 
other  of  the  organs,  even  the  brain.  The  woolsorters'  disease, 
or  pulmonary  form,  occurs  from  inhaling  bacilli  into  the 
lungs.  The  bacteria  also  enter  by  swallowing,  or  by  wounds 
and  cracks.  The  pulmonary  form  is  always  fatal  while  the 
superficial  variety,  although  serious,  is  much  less  grave  in 
prognosis.  However  they  enter  the  germs  spread  by  con- 
tiguity or  by  the  lymph.  Their  chief  action  is  local  and  they 
do  not  enter  the  blood  stream  except  near  death.  They  do 
not  settle  in  one  place  and  remain  there,  but  may  pass  from 
one  localization  to  another.  While  most  of  the  noxious  effect 
is  mechanical  the  anthrax  bacillus  seems  to  produce  a  little 
extracellular  toxin  which  has  the  power  to  attack  tissue  and 
cause  the  accumulation  of  edema  and  blood.  The  softenings 
are  due  to  the  killing  effect  of  the  bacillus  poisons  upon  the 


BACTERIUM  ANTHRAClS  153 

tissues.  This  solvent  action  also  attacks  the  walls  of  blood- 
vessels permitting  the  leaking  of  blood  or  a  true  hemorrhage. 
The  poisons  are  further  absorbed  by  the  circulation  with  a 
resulting  fever  and  general  illness.  The  bacteria  may  leave 
the  body  with  pus  or  sloughs,  by  the  expectoration  in  the 
pulmonary  form,  or  by  the  feces  when  the  infection  is  intes- 
tinal or  has  become  generalized.  Because  of  the  rarity  and 
severity  of  this  infection  of  human  beings  it  is  of  little 
importance  in  the  transmission  to  others.  Infected  animals 
and  hides  or  brushes  made  from  bristles  of  infected  animals 
are  by  all  means  the  most  important  factors  in  the  contrac- 
tion of  the  disease  by  man  and  the  Government  has  formu- 
lated special  rules  covering  the  inspection  of  abattoirs, 
tanneries  and  brush  making  so  that  dangerous  animal 
products  may  not  be  distributed. 

Protection  against  anthrax  is  secured  with  difficulty  since 
its  organisms  produce  resistant  spores.  The  sputum,  feces, 
and  wound  discharges  should  be  so  received  that  immediate 
burning  is  possible.  Chemical  disinfection  is  much  less 
reliable.  Five  per  cent,  carbolic  acid  should  be  allowed  to 
remain  in  contact  with  infective  material  for  two  days. 
Corrosive  sublimate,  1  to  1000,  for  one  day  is  usually  suffi- 
cient. 

Anthrax  is  diagnosticated  by  finding  the  bacteria,  not  a 
very  difficult  matter,  since  they  grow  with  comparative 
luxuriance  on  laboratory  media.  Smears  also  assist,  because 
of  the  characteristic  appearance  of  the  rods. 

Morphology  and  General  Characteristics. — The  anthrax 
bacillus  is  a  large  straight  rod  with  sharply  cut  ends.  It 

measures  rsToo  to  YoVo  incn  l°ng  by  25000  to  ToToo  incn 
wide.  It  does  not  possess  motility,  but  does  form  round,  oval, 
or  elliptical  spores,  situated  near  the  center  of  the  rod.  The 
bacilli  may  grow  in  chains  suggesting  bamboo  sticks.  They 
require  oxygen.  The  rods  but  not  the  spores  are  easy  to 
stain.  There  is  a  delicate  capsule  about  the  organisms  when 
stained  in  pus.  They  grow  best  at  37°  C.  or  98°  F.,  but  also  at 


154     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

lower  temperatures.  The  vegetative  rods  are  killed  at  54°  C. 
or  130°  F.  in  ten  minutes;  the  spores  are  killed  by  boiling  ten 
minutes  or  in  dry  heat  at  140°  C.  or  285°  F.  for  ten  minutes. 
The  resistance  to  chemical  agents  has  been  considered  under 
Disinfectants,  but  it  is  best  not  to  rely  on  any  chemical 
killing  of  anthrax  spores,  as  different  cultures  vary  in  resist- 
ance and  the  environment  plays  an  important  part.  Anthrax 
bacilli  grow  well  and  characteristically  on  laboratory  culture 
media.  It  has  been  found  possible  to  produce  an  antiserum 
which  has  some  beneficial  effect  on  the  human  disease  but 
it  must  be  given  early  and  only  acts  as  an  aid  to  the  surgical 
treatment  which  can  never  be  omitted.  One  of  the  great 
achievements  of  Pasteur  was  the  discovery  of  a  method  of 


FIG.  47. — Threads  of  Bacterium  anthracis  containing  spores.    X  about 
1200  diameters.     (Abbott.) 

immunizing  sheep  against  anthrax.  He  discovered  that  by 
growing  anthrax  bacilli  at  a  temperature  of  42°  C.  or  106°  F. 
instead  of  37°  C.  or  98°  F.  he  was  able  to  reduce  their  viru- 
lence considerably.  By  varying  the  length  of  time  of  culti- 
vation at  this  temperature  two  different  strengths  were 
obtained.  He  now  injected  the  weaker,  and  followed  a  few 
days  later  with  the  more  virulent.  The  resistance  of  the 
animal  can  thus  be  raised  to  a  high  level  for  about  a  year. 
The  method  is  not  practicable  for  human  beings. 


ACTINOMYCOSIS 


ACTINOMYCOSIS. 

Actinomycosis  or  lumpy  jaw  is  chiefly  a  disease  of  animals, 
but  may  affect  man.    It  is  characterized  by  the  production 


ACTINOMYCOSIS 


155 


of  large  semisolid  tumefactions  usually  in  the  upper  air  pas- 
sages or  their  neighboring  tissues  and  in  the  lungs.  It  may 
spread  under  the  skin  or  into  organs.  The  bones  of  the  jaw 
are  usually  involved.  Any  bone  in  the  path  of  progression 
of  the  disease  may  be  infiltrated.  The  organisms  causing  it 
belong  to  the  higher  bacteria,  and  are  called  Streptothrix 
actinomyces,  Actinomyces  bovis  or  ray  fungus,  because  of  their 
tendency  to  spread  out  in  rays.  The  organism  enters  by 
way  of  the  mouth  or  nose  into  cracks  or  wounds.  Associa- 


FIG.  48. — Actinomyces  fungus  ("ray  fungus"):  left,  as  seen  in  tissues 
under  low  magnifying  power;  right,  a  fungus  mass  examined  fresh  under 
higher  magnifying  power.  (Abbott.) 

tion  with,  or  eating  uncooked  meat  of  animals  having  the 
disease  is  the  method  of  infection  in  man.  The  disease 
remains  infectious  as  long  as  there  are  open  lesions,  dis- 
charging bacilli.  No  quarantine  is  needed  provided  the 
patient  is  under  proper  supervision. 

When  the  germs  enter  they  start  to  proliferate  and  excite  a 
nodule  not  unlike  that  of  tuberculosis.  It  spreads  by  con- 
tinuity outward  and  involves  adjoining  structures.  The 
center  of  the  nodules  softens  into  caseous  matter  in  which 
small  white  or  gray  masses  of  the  bacterial  growth  may  be 


156     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

found.  This  is  the  chief  source  of  material  by  which  the 
diagnosis  is  made.  The  large  tumors  ulcerate  through  the 
skin  at  times  and  present  sloughing  areas.  This  is  the  manner 
also  in  which  the  infecting  germ  leaves  the  body.  In  diag- 
nosticating the  disease  one  of  the  small  granules  in  the  pus 
is  taken,  crushed  beneath  a  glass,  and  examined  directly 
under  the  microscope  for  the  ray  fungus.  The  specimen 
may  also  be  stained. 

Infective  material  from  abscesses  or  ulcers  or  the  sputum 
should  be  burned.  Chemical  destruction  is  less  reliable. 
Ordinary  care  of  the  hands  will  suffice  as  a  protection,  but 
no  lack  of  care  is  justifiable.  It  is  not  a  very  infectious  dis- 
ease, but  a  serious  one  and  one  of  long  duration.  The  pecu- 
liar changes  in  this  disease  are  due  to  the  life  and  growth  of 
the  fungus  as  a  foreign  body  and  probably  not  to  any  peculiar 
toxin.  No  immunity  or  peculiar  blood  changes  follow  an 
attack.  The  treatment  is  surgical  and  medical,  the  latter 
being  confined  to  the  use  of  potassium  iodide. 

Morphology  and  General  Characteristics. — The  organism  of 
actinomycosis  is  in  the  form  of  interwoven  threads,  radiat- 
ing from  a  center,  having  thickened  or  bulbous  ends.  These 
ends  are  important,  as  they  assist  in  species  determination 
and  possibly  have  something  to  do  with  multiplication  of 
the  germ.  The  threads  are  about  7 5 1 0 0  to  50ooo  inch  wide, 
their  length  being  very  variable.  The  bulbs  measure  from 
eoooo  to  30*00  inch  in  width  and  vary  in  length.  They 
grow  with  reasonable  freedom  in  the  laboratory,  especially 
upon  media  containing  animal  substances  such  as  blood 
serum.  Their  optimum  temperature  is  40°  C.  or  102°  F. 
They  are  killed  at  75°  C.  or  167°  F.  exposed  ten  minutes. 
They  resist  drying  for  a  long  time.  They  are  extremely 
resistant  to  chemical  disinfectants.  Not  all  animals  are 
susceptible  to  actinomycosis,  but  those  contracting  it  present 
about  the  same  type  of  lesions.  Nothing  in  their  blood 
serum  is  of  any  value  in  treatment  of  human  beings.  Vaccines 
are  not  used. 


CHAPTER  XI. 

VARIOUS  PATHOGENIC  BACTERIA  NOT 

ASSOCIATED  WITH  A  SPECIFIC 

CLINICAL  DISEASE. 

THERE  is  a  large  class  of  bacteria  capable  of  producing 
various  inflammations  or  infections  that  do  not  follow  a 
constant  or  even  uniform  course.  Surgically  speaking,  they 
are  probably  the  most  important  group  aside  from  the  pus 
cocci.  It  is  not  possible  to  make  many  generalizations  con- 
cerning these  organisms.  The  results  of  infection  with  them 
vary  greatly,  depending  first  upon  their  own  virulence  and 
second  upon  the  resistance  of  their  host.  Biologically,  many 
of  these  non-specific  germs  bear  a  close  relationship  to 
species  giving  a  very  definite  clinical  disease.  In  the  first 
example,  the  colon  bacillus,  this  is  well  illustrated.  A  certain 
group  of  bacteria  is  spoken  of  as  the  typhocolon  series. 
This  means  that  they  possess  characteristics  relating  them 
to  one  another.  Certain  members  of  the  series  can  be 
separated  only  by  very  careful  technic,  yet  they  are  capable 
of  setting  up  easily  distinguishable  affections. 

THE  TYPHOCOLON  BACILLI. 

% 

The  colon  bacillus  is  the  common  normal  inhabitant  of 
animal  intestines,  particularly  of  the  colon,  whence  it  derives 
its  name.  The  group  of  bacteria,  the  typhocolon  series,  to 
which  this  organism  belongs  and  of  which  it  and  the  typhoid 
bacillus  are  the  most  conspicuous  representatives,  embraces 
many  species,  subspecies,  and  varieties.  A  botanical  and 
chemical  classification  satisfactory  to  all  authorities  has  not 

(157) 


158  PATHOGENIC  BACTERIA 

yet  been  made.  It  can  be  said  in  general  that  all  members 
of  this  group  find  the  intestinal  tract  a  suitable  place  for  life, 
some  under  normal,  others  under  pathological  conditions. 
Old  classifications  of  the  typhocolon  group  admitted  only 
organisms  capable  of  motion,  but  some  later  observers 
include  many  non-motile  and  even  encapsulated  forms. 
Inasmuch  as  a  very  close  separation  on  the  basis  of  techni- 
calities is  not  necessary  in  this  work,  it  has  been  deemed 
best  to  choose  the  principal  clearly  defined  species  for  descrip- 
tion. Such  descriptions  permit  of  extension  in  a  general  way 


FIG.  49. — Colon  bacilli.     Twenty-four-hour  agar  culture.     X  1100 
diameters.     (Park.) 

to  the  nearest  congeners,  and  therefore  we  may  say  that  we 
are  considering  types.  The  typhoid  and  paratyphoid  bacilli 
have  been  sufficiently  described  in  Chapter  IX. 

The  Colon  Bacillus. — The  colon  bacillus  proper,  called  also 
the  Bacillus  coli  communis,  is  a  non-spore-bearing,  sluggishly 
motile,  delicate  rod,  measuring  from  25000  to  8~oVo  mcn  m 
length  and  60ioo  to  30000  mcn  in  width.  It  appears  when 
stained  as  a  single  rod  usually,  but  occasionally  in  pairs  or 
short  chains.  It  takes  the  laboratory  dyes  with  ease,  usually 
more  deeply  near  its  rounded  ends.  It  moves  by  flagella 


THE  TYPHOCOLON  BACILLI  159 

arranged  all  about  the  cell  wall.  It  grows  with  ease  artificially, 
best  in  the  presence  of  oxygen,  but  also  in  its  absence.  Devel- 
opment will  occur  at  any  temperature  from  10°  to  43°  C.  or 
50°  to  108°  F.  It  produces  no  spores.  No  color  or  pigment 
is  developed  when  cultivated  in  the  laboratory.  It  possesses 
the  power  of  coagulating  milk  and  of  acid  fermentation,  with 
the  production  of  gas,  in  most  of  the  carbohydrates  (sugars 
and  starches)  used  for  the  differentiation  of  bacteria.  It 
does  not  produce  ferments  capable  of  liquefying  gelatin  or 
the  milk  curd.  It  does,  however,  break  up  simpler  substances 
and  forms  indol,  a  putrefaction  product. 

The  colon  bacillus  is  killed  at  60°  C.  or  140°  F.  in  ten 
minutes.  It  resists  freezing  for  a  long  time,  perhaps  several 
months.  Drying  usually  kills  in  one  day,  but  certain  indi- 
viduals may  remain  viable  for  many  days  or  weeks.  It  is 
killed  by  carbolic  acid,  1  to  1000,  in  twenty  minutes,  or  5 
per  cent,  in  two  minutes  in  watery  suspension.  About  the 
same  times  hold  for  bichloride  of  mercury,  1  to  4000  and  1 
to  1000.  To  weak  acids  it  is  resistant,  as  is  shown  by  its 
passage  in  food  through  the  hydrochloric  acid  of  the  stomach. 
This  is  also  true  of  the  typhoid  bacillus.  It  will  multiply  in 
feebly  acid  or  alkaline  solutions.  Direct  sunlight  kills  almost 
at  once,  while  diffuse  light  is  withstood  for  a  long  time. 

The  colon  bacillus  is  found  in  the  intestines  of  man  and 
animals  in  health  or  disease.  It  is  expelled  with  the  feces 
and  therefore  gets  into  water-courses.  The  bacilli  may  be 
found  in  the  superficial  layers  of  the  earth.  Examination 
of  water  for  public  health  purposes  aims  at  its  discovery  as 
an  indication  of  sewage  pollution.  Its  presence  in  milk  may 
be  accounted  for  by  contamination  of  milk  in  cans  washed 
with  polluted  water.  It  should  not  be  forgotten  that  despite 
the  greatest  personal  care,  colon  bacilli  are  widely  distributed 
on  everything  that  comes  in  contact  with  man  and  animals. 
The  newborn  baby's  intestine  is  free  of  them,  but  does  not 
long  remain  so,  as  the  organisms  find  their  way  in  with  food 
from  the  hands  of  attendants,  or  possibly  through  the  anus 


160  PATHOGENIC  BACTERIA 

and  up  the  rectum.  The  colon  contains  most  of  the  bacilli 
and  the  number  decreases  upward  in  the  small  intestine 
until  in  the  stomach  they  are  rarely  found.  They  may, 
however,  at  times  enter  the  liver  by  means  of  the  bile  pas- 
sages or  portal  vein  system. 

The  consistency  with  which  the  colon  bacilli  are  present 
in  the  intestine  raises  the  question  as  to  their  function  or 
value  there.  This  is  probably  best  answered  today  by  saying 
that  they  assist  in  controlling  the  growth  of  certain  putre- 
factive bacteria,  and  that  they  may  assist  somewhat  in 
breaking  up  simple  substances  so  that  these  may  be  more 
easily  absorbed. 

The  toxin  of  the  colon  bacillus  is  within  its  body,  no  extra- 
cellular poison  being  formed.  If  one  inject  the  dead  organism 
into  an  animal  in  sufficient  number,  mucous  membrane  irri- 
tation, paralyses,  and  convulsions  may  occur.  Living  bacilli 
introduced  into  the  peritoneum  cause  peritonitis  and  septi- 
cemia,  the  organisms  entering  the  blood  stream.  An  abscess 
will  usually  result  if  they  are  brought  under  the  skin.  In 
man  colon  bacilli  seldom  go  beyond  the  mucous  membrane 
of  the  intestine  because  of  the  resistance  offered  by  that  tissue. 
After  death  the  organisms  rapidly  invade  the  different  organs 
of  the  body.  Whenever  the  resistance  of  the  body  is  reduced 
an  opportunity  is  presented  for  the  spread  of  these  organisms. 
When  for  any  reason  the  colon  bacillus  gains  in  virulence  or 
the  resistance  of  the  intestinal  wall  decreases,  there  arise 
inflammation  of  the  mucous  membrane  of  the  intestine,  a 
swelling  of  Peyer's  plaques  comparable  to  that  seen  in  typhoid 
fever,  and  these  changes  permit  the  bacteria  to  spread  in  the 
body.  There  may  arise  inflammation  of  the  gall-bladder,  the 
pelvis  of  the  kidney,  or  abscesses  in  various  parts  of  the  body. 
Cystitis  may  occur,  which  may  be  a  part  of  a  general  infec- 
tion, descend  from  the  kidney,  or  arise  from  introduction  of 
the  organisms  through  the  urethra.  An  ascending  infection 
from  the  bladder  to  the  pelvis  of  the  kidney  and  on  into  the 
substance  of  the  organ  is  not  an  uncommon  disease  process. 


THE  TYPHOCOLON  BACILLI  161 

This  frequently  occurs  in  pregnancy  or  after  labor.    The  colon 
bacillus  is  the  commonest  single  organism  to  cause  pyelitis. 

The  inflammations  of  the  gall-bladder  and  its  passages  and 
of  the  liver  may  arise  either  from  introduction  of  bacilli  up 
the  common  bile  duct,  or  as  a  part  of  colon  bacillus  septicemia. 
The  peritonitis  seen  after  perforation  of  the  intestines  is  the 
result  of  many  kinds  of  bacteria  of  which  the  colon  bacillus 
may  be  the  most  numerous.  It  is  probable  that  this  organism 
alone  is  able  to  inflame  the  peritoneum,  as  it  certainly  can 
produce  localized  and  diffuse  pus  collections.  The  colon 
bacillus  is  frequently  the  only  organism  found  in  acute 
appendicitis.  It  has  been  found  as  an  important  factor  if 
not  the  sole  cause  in  pneumonia  and  pleurisy.  It  has  been 
found  to  cause  meningitis  and  endocarditis. 

No  antiserum  of  practical  value  has  been  produced  by  the 
injection  of  these  organisms  into  the  lower  animals.  On  the 
other  hand,  some  success  has  been  attained  in  establishing 
active  immunity  both  as  a  preventive  and  as  a  remedial 
agency  by  injecting  increasing  quantities  of  dead  bacteria. 

Diagnosis. — Colon  infections  are  diagnosticated  chiefly  by 
finding  the  organism.  They  are  present  in  the  fibrinous  exu- 
date  or  pus,  and  in  the  blood  in  septicemia.  We  grow  some  of 
this  in  ordinary  nutrient  broth  or  jelly,  and  isolate  in  pure 
culture.  Colon  bacilli  are,  of  course,  easily  obtained  from  the 
stools.  The  agglutination  or  clumping  test  can  also  be  used 
in  colon  bacillus  infections,  since  agglutinins  are  formed 
during  an  attack.  Pus  or  other  bacteria-containing  substance 
should  be  disinfected  by  mixing  with  5  per  cent,  carbolic 
acid  and  allowing  it  to  act  for  at  least  one-half  hour. 

Paracolon  Bacilli. — These  organisms  resemble  the  Bacillus 
coli  communis  so  closely  that  only  the  differences  need  be 
noted.  They  are  more  actively  motile,  they  do  not  coagulate 
milk  but  probably  produce  alkalinity  in  it;  they  are  capable 
of  producing  acid  and  gas  in  only  three  of  the  sugars.  They 
differ  from  the  paratyphoid  bacilli  in  their  action  upon 
milk  and  their  greater  ability  to  ferment  the  carbohydrates. 
11 


162  PATHOGENIC  BACTERIA 

These  two  groups,  the  paracolons  and  paratyphoids  (see  page 
116),  are  called  the  intermediates  between  the  true  typhoids 
and  colons.  Their  cultivation  is  performed  as  outlined  for 
the  colon  bacillus.  The  typical  species  of  this  group  is  the 
Bacillus  enteritidis  of  Gartner  or  the  meat-poisoning  organism. 

The  disease  produced  by  this  bacterium  is  usually  very 
acute,  but  in  infections  by  some  members  of  this  group  the 
disease  may  last  nearly  as  long  as  paratyphoid  fever.  The 
bacteria  are  present  in  meat,  probably  within  the  animal 
before  slaughter.  In  Europe  where  the  refrigerating  systems 
are  less  complete  than  in  this  country,  meat  passes  from  the 
butcher  to  the  consumer  directly,  and  therefore  there  may  be 
epidemics  when  infected  cattle  are  slaughtered. 

The  bacteria  pass  into  the  intestines,  are  absorbed  by 
their  walls,  and  pass  into  the  blood  stream.  The  infection 
gives  diarrhea  of  the  typhoid  or  cholera  type,  prostration,  and 
sometimes  delirium.  The  disease  is  usually  transmitted  only 
by  meat  in  the  form  of  cuts  or  as  sausage,  and  these  foods 
are  unaltered  in  color  and  taste  by  the  presence  of  the 
bacteria. 

The  toxin  is  peculiar  in  that  it  resists  cooking  sufficient  to 
destroy  the  life  of  the  bacilli  and  drying  or  smoking  does  not 
diminish  its  power.  It  is  an  endotoxin.  The  bacillus  may 
form  pus,  and  the  author  has  seen  it  as  the  cause  of  a  diffuse 
pelvic  inflammation.  When  injected  into  animals  the  para- 
colon  bacilli  are  capable  of  giving  rise  to  a  fatal  septicemia 
with  acute  inflammations,  hemorrhages,  and  collapse.  The 
bacilli  are  found  chiefly  by  examination  of  the  stools  or  by 
cultivation  of  the  circulating  blood  or  material  from  abscesses. 
Infective  material  should  be  rendered  innocuous  by  the  means 
outlined  for  the  colon  and  typhoid  bacilli  (p.  114). 

A  very  important  means  of  diagnosis  with  all  the  infections 
of  the  typhocolon  group  is  the  agglutination  test.  These 
congeners  produce  agglutinins  having  some  affinity  for  all 
members  of  the  group.  The  method  of  use  in  this  test  consists 
in  finding  that  member  of  the  group  that  will  be  clumped  by 


MUCOSUS  CAPSULATUS  GROUP  163 

the  greatest  dilution  of  the  patient's  serum.  This  organism 
is  then  considered  the  causative  one.  No  practical  remedy 
has  been  found  by  the  use  of  antitoxins  or  vaccines. 

MUCOSUS  CAPSULATUS  GROUP. 

This  group  has  been  included  with  the  colons  by  many 
of  the  later  writers.  Such  a  classification  is  open  to  some 
objection,  but  it  is  quite  proper  to  discuss  the  organisms 
directly  after  the  colon  group,  since  the  two  types  have  some 
things  in  common  and  both  are  constantly  present  in  the 
intestinal  tract. 

The  bacteria  in  question  are  non-motile,  plump,  straight 
rods  without  spores,  but  surrounded  by  a  capsule,  at  least 
when  in  the  animal  body.  They  measure  from  3  5- 1 0  0  to 
s-oVo  inch  in  length  and  from  50iUo  to  FeWo  inch  in 
width.  They  may  be  found  lying  singly,  but  when  in  the 
body  are  commonly  united  in  pairs  or  short  chains  about 
which  one  may  find  the  capsule.  We  may  find  the  capsule  in 
milk  or  gelatin  cultures.  They  are  easily  stained  by  ordinary 
dyes.  They  grow  well,  best  at  body  temperature,  but  also  as 
low  as  12°  C.  or  54°  F.,  or  as  high  as  41°  C.  or  106°  F.  They 
are  killed  at  56°  C.  or  133°  F.  in  ten  minutes.  They  resist 
drying  quite  well.  Freezing  is  rather  rapidly  fatal  to  them. 
They  grow  best  in  the  presence  of  oxygen,  but  may  live  with- 
out it.  All  the  artificial  cultivations  of  this  group  are  char- 
acterized by  luxuriance,  with  a  tendency  to  a  slimy,  smeary, 
or  tenacious  consistency,  hence  the  name  "mucosus."  None 
of  the  group  can  soften  gelatin  or  make  indol.  They  all 
produce  some  degree  of  acidity  in  milk,  but  not  all  can  curdle 
it.  The  various  members  behave  very  differently  in  regard  to 
sugars,  and  upon  these  reactions  they  are  classified. 

The  poison  produced  by  the  bacteria  of  this  group  is  prob- 
ably all  endotoxic.  They  irritate  the  part  also  mechanically 
by  their  presence.  These  bacilli  are  widely  distributed  in 
animal  life,  but  less  so  otherwise  in  nature.  They  are  trans- 


164  PATHOGENIC  BACTERIA 

mitted  directly  from  man  to  man,  by  particles  of  saliva  or 
sputum  or  in  fecal  discharges,  or  in  pus,  which  should  be  dis- 
infected as  given  for  the  colon  bacillus.  Besides  the  special 
conditions  to  be  mentioned  later,  members  of  this  group  have 
been  known  to  cause  pyelitis,  gastro-enteritis,  peritonitis, 
pleuritis,  and  septicemia. 


v       % 

'  FIG.  50. — Bacillus  mucosus  capsulatus.     (Hiss  and  Zinsser.) 

The  most  important  member  of  the  group  is  the  Bacterium 
pneumonias  of  Friedlander,  a  cause  of  pneumonia  next  to 
the  pneumococcus  in  importance  for  the  acute  lobar  form. 
The  pneumonia  is  characterized  by  its  sticky  nature.  It  is 
usually  short  in  duration  and  grave  in  prognosis.  The  bacilli 
may  enter  the  circulation  and  give  rise  to  localized  inflam- 
mations, including  abscesses,  elsewhere  in  the  body.  It  has 
been  known  to  cause  nasal  sinus  trouble,  otitis  media,  endo- 


MUCOSUS  CAPSULATUS  GROUP  165 

carditis,  and  meningitis.    The  bacteria  are  found  by  blood 
or  sputum  culture.    Agglutination  tests  are  not  of  value. 

Two  other  members  of  this  group  associated  with  disease 
in  man  are  Bacterium  rhinoscleromatis  and  Bacterium  ozenoe. 
The  former  is  said  to  cause  a  slow  granulomatous  inflamma- 
tion on  the  nose,  mouth,  or  larynx,  in  which  hard  nodular 
swellings  are  formed,  containing  large  typical  cells  loaded  with 
bacilli.  Bacterium  ozence  is  associated  with  fetid  atrophic 
rhinitis  or  nasal  catarrh. 


FIG.  51. — Bacillus  of  rhinoscleroma.     Section  of  tissue  showing  the  micro- 
organisms within  Mikulicz  cells.     (After  Frankel  and  Pfeiffer.) 

All  the  mucosus  group  are  moderately  pathogenic  for 
animals,  but  injections  into  these  experimentally  do  not  call 
forth  prototypes  of  the  diseases  in  man.  Usually  a  septi- 
cemia  with  extensive  fibrin  deposit  on  serous  membranes 
results.  The  thick,  stringy,  or  viscid  character  of  the  exu- 
dates  is  peculiar  to  these  bacteria.  No  antiserum  has  been 
produced  to  use  in  cases  of  disease  caused  by  them,  but  there 
have  been  some  favorable  results  after  injecting  dead  organ- 
isms during  an  attack. 


166 


PATHOGENIC  BACTERIA 


Bacterium  Bulgaricum. — Another  organism  not  far  removed 
from  the  group  just  described,  of  practical  if  not  of  pathogenic 
importance,  is  the  milk-souring  bacillus.  There  are  many 
varieties,  but  the  one  now  used  most  is  the  Bacterium  bul- 
garicum  of  Massol.  It  has  the  property  of  breaking  up  the  fat 
of  milk  and  producing  lactic  acid.  This  buttermilk  or  sour 
milk  is  used  in  intestinal  diseases  (see  p.  35)  at  the  suggestion 
of  Metchnikoff.  The  large  quantity  of  lactic  acid  is  inimical 


FIG.  52. — Bacterium  bulgaricum.     X  1000  diameters.     (Piffard.) 

to  many  disease-producing,  putrefactive,  and  fermenting 
bacteria  that  elaborate  poisons,  the  absorption  of  which 
leads  to  intoxication  to  which  Metchnikoff  ascribed  senility 
and  some  specific  diseases.  This  observer  believed  that  the 
health  of  certain  people  of  the  Balkan  States  could  be  ascribed 
to  drinking  fermented  mares'  milk  (koumyss).  The  various 
sour  milks  now  on  the  market  are  made  by  inoculating  milk 
with  organisms  of  this  kind.  They  are  probably  not  superior 
to  domestically  prepared  buttermilk,  if  one  has  a  good  culture 


MUCOSUS  CAPSULATUS  GROUP  167 

of  the  proper  organism  to  start  with,  except  that  they  are 
apt  to  be  more  uniform  in  content  of  lactic  acid.  The  writer 
prefers  to  give  whey  cultures  of  the  Bulgarian  bacillus  so  that 
one  can  always  know  how  many  organisms  are  being  used. 

The  organism,  a  large  one  from  12Q00  to  ^-5-  inch  in  length 
grows  in  chains,  best  at  44°  C.  or  111°  F.  in  milk,  but  may  be 
cultivated  on  other  media.  The  souring  of  milk  takes  place 
within  twenty-four  hours  if  the  temperature  be  correct.  (See 
Chapter  on  Milk.) 

Bacillus  Aerogenes  Capsulatus  of  Welch. — A  very  important 
putrefactive  organism  in  the  intestine  is  the  Bacillus  aerogenes 
capsulatus  of  Welch.  This  organism  grows  only  in  the 
absence  of  oxygen.  It  is  a  large,  straight,  or  slightly  curved 
rod,  from  25Q00  inch  up  to  3^0  inch  long  by  about  30ooo 
inch  wide,  non-motile,  and  encapsulated.  It  has  the  power  of 
fluidifying  gelatin  and  clotting  milk.  It  is  introduced  to  the 
human  body  by  wounds  probably,  or  it  may  go  out  from  the 
intestinal  tract  through  a  solution  of  the  mucous  membrane. 
When  lodging  in  the  organs  it  forms  gases,  giving  an  appear- 
ance to  the  liver  called  a  foam  or  sponge  liver.  It  has  an 
importance  in  obstetrics,  as  gas-infection  sometimes  appears 
after  mechanical  treatment  within  the  uterus.  It  is  probably 
not  pathogenic  to  entirely  healthy  tissue,  but  when  an  injury 
devitalizes  a  part  an  entrance  is  afforded.  It  is  responsible 
for  the  early  bloating  of  some  cadavers. 

This  bacterium  has  attained  considerable  importance  be- 
cause of  the  number  of  infections  with  it  in  the  Great  War. 
Many  of  the  wounds,  especially  those  due  to  bursting  shells, 
penetrate  deeply  into  and  lacerate  tissues,  thus  supplying  a 
favorable  place  for  these  organisms  to  develop.  The  bacillus 
of  Welch  is  widely  distributed  in  soil,  which  is  carried  into  the 
wounds.  Gas  is  formed  in  the  devitalized  tissue  and  some 
toxin  elaborated  by  the  germ  gives  constitutional  symptoms. 
It  is  probable  that  the  presence  of  these  organisms  favors  the 
growth  of  others.  It  has  been  discovered  that  the  bacillus 
produces  extracellular  toxin  and  that  an  antitoxin  will  be 


168  PATHOGENIC  BACTERIA 

formed  by  repeated  injection  of  this  into  horses.  This  anti- 
toxin has  been  used  prophylactically  as  well  as  therapeuti- 
cally  and  it  has  been  decided  to  inject  it  with  the  preventive 
tetanus  antitoxin  on  the  battlefield  in  all  cases  of  penetrating 
wounds.  Disinfection  of  material  from  this  condition  requires 
the  burning  of  all  dressings.  It  is  the  practice  of  surgeons 
to  remove  all  the  tissue  devitalized  by  a  missile  to  remove 
bacteria  and  damaged  muscle  upon  which  bacteria  will  grow, 
and  because  the  freshly  trimmed  healthy  tissue  will  heal 
better;  all  pieces  removed  would  better  be  burned,  but  the 
chlorine  disinfectants  will  answer  where  this  is  not  prac- 
ticable. 

Bacillus  of  Malignant  Edema. — The  bacillus  of  malignant 
edema  is  a  common  inhabitant  of  the  soil  and  may  be  found  in 
dust.  It  grows  only  in  the  absence  of  free  oxygen,  but  may  be 
cultivated  with  ease  in  the  laboratory,  particularly  if  sugar 
be  added  to  the  medium.  It  is  a  long,  delicate  rod,  measuring 
about  25000"  inch  in  thickness  and  8Q0()  to  3 ^ 0  inch  in 
length.  It  moves  by  flagella  arranged  along  the  sides.  Spores 
are  formed  about  the  middle  of  the  length.  These  spores  are 
responsible  for  the  great  resistance  presented  by  the  germ. 
The  pathological  properties  are  due  to  a  soluble  separ- 
able toxin.  The  bacteria  themselves  do  not  enter  the  blood 
stream.  At  the  site  of  inoculation  an  edematous  and  bloody 
swelling  appears  which  in  susceptible  individuals  spreads 
rapidly.  Death  results  from  toxemia*  This  germ  is  fre- 
quently responsible  for  spontaneous  disease  in  the  lower 
animals,  but  in  man  is  probably  only  introduced  by  some 
mechanical  injury.  It  has  been  known  to  be  introduced  by 
hypodermic  injections  when  a  dirty  needle  was  used.  Its 
most  common  method  of  introduction  is  in  grinding  dirt  into 
a  wound,  such  as  a  compound  fracture.  All  discharges  or 
dressings  should  be  so  received  that  they  can  be  burned. 

Bacillus  Proteus  Vulgaris. — The  Bacillus  proteus  mdgaris 
is  a  widely  distributed  organism  of  pronounced  putrefactive 
powers.  It  is  very  similar  to  the  colon  bacillus.  It  has  been 


MUCOSUS  CAPSULATUS  GROUP  169 

encountered  in  abscesses,  pyelonephritis,  endometritis,  and 
peritonitis.  Meat  poisonings  have  been  traced  to  it.  Its 
toxin  is  very  poisonous.  It  is  frequently  a  harmless  inhabi- 
tant of  the  intestinal  tract.  It  is  quite  resistant,  and  to  kill 
it  requires  the  most  approved  disinfectants  acting  over  a 
considerable  time. 

Bacillus  Pyocyaneus. — Bacillw  pyocyaneus  is  the  organism 
of  green  pus.  This  bacterium  is  widely  distributed  on  the 
skin  and  mucous  membranes  of  man  and  animals.  Its 
disease-producing  powers  are  low  and  considerable  reduction 


FIG.  53. — Bacillus  pyocyaneus.     (From  Kolle  and  Wassermann.) 

of  resistance  on  the  part  of  the  host  may  be  assumed  when 
infection  occurs.  It  may  enter  by  cracks  or  wounds,  and  not 
infrequently  is  associated  with  other  bacteria,  notably  the 
pus  cocci.  The  pyocyaneus  bacillus  is  an  actively  motile, 
straight,  or  slightly  curved,  non-spore-forming  rod  measuring 
from  25000  inch  to  %QQQ  inch  long  and  75ooo  inch  wide. 
Its  motility  is  due  to  one  flagellum  placed  at  one  end. 

It  grows  readily  at  room  or  body  temperature,  best  in 
the  presence  of  oxygen.  On  agar  jelly  it  forms  pigments 
which  color  the  growth  itself  and  the  medium  upon  which 
it  is  living.  These  pigments  are  of  two  kinds,  a  green  one 


170  PATHOGENIC  BACTERIA 

and  a  fluorescent  one.  They  impart  a  beautiful  green  fluores- 
cence to  the  tube  of  culture  material.  The  bacillus  has  the 
power  to  elaborate  a  gelatin-digesting  and  a  milk-curdling 
ferment.  Its  powers  of  resistance  to  heat  and  chemicals  are 
rather  high.  Materials  to  be  disinfected  should  be  exposed  to 
carbolic  acid  or  formaldehyde  solutions  for  half  an  hour. 

The  poisons  of  the  pyocyaneus  bacillus  are  twofold — 
one  an  endotoxin,  the  other  a  soluble  separable  toxin.  These 
substances,  more  especially  the  latter,  have  the  power  of 
destroying  some  other  bacteria.  The  broth  culture,  freed  of 
bacteria  and  reduced  to  one-tenth  its  volume,  then  called 
pyocyanase,  is  used  sometimes  to  rid  the  throat  of  persistent 
diphtheria  bacilli.  The  toxins  are  more  poisonous  to  animals 
than  are  the  living  cultures.  Most  small  laboratory  animals 
are  susceptible  to  injections  of  the  living  pyocyaneus  bacillus. 
The  bacilli  may  multiply  within  the  body  and  enter  the  blood 
stream.  It  is  maintained  that  some  part  of  the  toxin  has  the 
power  to  destroy  red  blood  cells. 

The  pyocyaneus  bacillus  may,  by  its  presence  on  wounds, 
delay  their  healing.  It  is  commonest  perhaps  in  boils  in  the 
axilla  and  groin.  It  has  been  found  in  otitis  media  and  in 
gastro-enteritis  of  debilitated  children.  There  may  be  a 
general  sepsis,  under  which  circumstances  pleurisy,  peri- 
carditis, and  the  like  may  be  looked  for.  A  diagnosis  is  made 
solely  by  finding  the  pigment- producing  bacillus  in  pus  or 
other  exudate,  or  possibly  by  blood  culture.  Active  immunity 
may  be  produced  in  the  lower  animals  by  exceedingly  careful 
technic,  but  it  has  not  been  found  profitable  to  use  the  anti- 
serum  upon  human  beings.  Vaccines  have  been  tried  in 
cases  of  old  abscesses,  sinuses  and  the  like  in  which  the 
pyocyaneus  bacillus  has  been  a  factor,  with  some  betterment, 
but  the  reaction  following  injections  is  severe  and  they  should 
be  used  only  by  persons  thoroughly  familiar  with  their 
actions. 


CHAPTER  XII. 
YEASTS  AND  MOULDS. 

THIS  chapter  is  devoted  to  a  consideration  of  the  next 
higher  groups  of  the  plant  algae  above  the  bacteria.  They 
are  the  yeasts  or  Blastomycetes  and  the  moulds  or  Hypho- 
mycetes.  That  there  is  any  sharp  separation  of  these  forms 
from  the  bacteria,  or  even  from  one  another,  cannot  be 
maintained.  There  are  various  gradations  in  character 
from  the  typical  representatives  of  the  groups  toward  the 
others,  so  that  there  are  intermediary  species  incapable  of 
classification.  The  typical  members  of  each  family  have 
very  distinct  criteria  and  about  them  similar  forms  must  be 
classified. 

The  yeasts  and  moulds  are  very  widely  distributed  in 
nature,  but  have  but  slight  pathogenic  powers.  The  former 
are  of  importance  in  the  making  of  spirituous  liquors,  bread, 
etc.  The  moulds  have  little  use,  and,  except  for  their  frequent 
appearance  as  contaminations,  and  in  a  few  diseases,  are  of 
little  interest  to  the  pathologist  or  bacteriologist. 

YEASTS. 

Yeasts  are  spherical  or  ovoid  bodies  with  a  doubly  con- 
toured wall  and  a  highly  granular  protoplasm  oftentimes  with 
fat  droplets  in  it.  They  measure  from  %^  to  y^  inch  in  length 
and  are  about  two- thirds  as  wide  as  long.  The  characteristic 
feature  of  the  yeasts  is  their  method  of  reproduction,  which 
takes  place  by  a  swelling  out  of  a  part  of  the  cell  wall  like  a 
ball,  into  which  the  protoplasm  flows;  this  is  called  "bud- 
ding." When  the  daughter-cell  arrives  at  the  proper  size, 

(171) 


172  YEASTS  AND  MOULDS 

the  connection  with  the  parent  dissolves  and  the  new  cell 
is  free.  Spores  have  been  observed  within  the  yeast  cells, 
and  these  develop  into  adult  cells  when  the  old  cell  ruptures. 
Yeasts  grow  upon  nearly  any  organic  substance  providing 
there  is  moisture.  The  best  media  and  temperatures  vary 
with  the  species.  The  kinds  pathogenic  for  man  grow  best 
upon  foodstuffs  containing  simple  sugars,  but  may  thrive 
also  on  complex  substances.  They  are  grown  with  reasonable 
ease  in  the  laboratory,  but  care  must  be  used  to  get  them  in 
pure  cultures  as  their  development  is  slow.  Their  peculiar 


/  <&  *#% 

/.•-sflNP 


FIG.  54. — Saccharomyces  Busse.    X  350  diameters.    (From  Kolle  and 
Wassermann.) 

effect  upon  carbohydrate-containing  stuffs  is  due  to  their 
enzyme  which  has  the  power  of  making  alcohol.  How  much 
effect  this  has  upon  the  production  of  disease  in  man  is  not 
known. 

Blastomycosis. — The  disease  produced  by  yeasts  in  man 
called  Blastomycosis,  and  the  causative  agent  is  called 
Saccharomyces  Busse,  after  the  man  who  first  described  it. 
By  the  first,  a  genus  name,  it  is  seen  to  belong  to  the  same 
group  as  the  principal  beer-making  yeast,  Saccharomyces 
cerevisice.  It  is  not  known  just  how  the  disease  is  contracted, 
but  the  yeast  probably  enters  wounds,  cracks,  or  hair  follicles. 


MOULDS  173 

It  penetrates  into  the  deep  layers  of  the  skin  and  sets  up 
abscesses  of  slow  development  and  spread.  These  may 
break  down  and  leave  a  sluggish  ulcer  which  later  shows  a 
tendency  to  heal.  More  serious  phases  of  this  infection  are, 
however,  met  when  the  lung  is  first  affected.  Then  a  pneu- 
monia, ending  in  sepsis,  results.  In  these  cases  the  outlook 
is  hopeless.  The  disease  is  probably  due  wholly  to  the 
mechanical  presence  of  the  yeasts.  The  germs  leave  the 
body  in  pus  or  sputum.  They  are  not  easily  destroyed,  and 
all  infective  matter  should  be  burned.  It  is,  however,  not  a 
very  contagious  disease. 

There  is  no  antiserum  treatment,  and  the  few  cases  upon 
which  vaccines  were  tried  have  not  held  out  much  promise 
in  this  direction.  Yeasts  are  held  responsible  for  some 
diseases  in  lower  animals,  but  the  question  is  not  yet  settled . 
When  injected  into  them  intentionally  varying  results  are 
obtained.  It  can  be  said  that  they  settle  by  preference  in 
the  lungs  and  spleen. 

MOULDS. 

This  group  is  by  no  means  so  simple  as  the  yeasts.  The 
following  remarks  pertain  to  those  forms  having  some  impor- 
tance in  human  medicine.  The  moulds  or  branching  fungi 
consists  of  long,  interlacing,  hair-like  threads  called  mycelia 
(sing.,  mycelium),  from  which  come  off  end  branches  called 
hyphse,  upon  which  the  reproducing  parts  usually  develop. 
These  mycelia  are  made  up  either  of  one  long,  continuous 
cell  with  a  cell  wall,  and  an  easily  distinguishable,  long 
nucleus,  or  they  may  break  up  into  shorter  forms  each  with 
a  separate  nucleus.  Their  length  and  width  are  so  variable 
that  measurements  would  be  misleading.  Their  general 
naked-eye  appearance  and  size  is  well  known  to  any  who 
have  observed  the  felt-like  or  cottony  moulds  upon  decaying 
organic  matter. 

Multiplication  occurs  in  two  ways.  Upon  the  hyphse 
may  develop  a  reproductive  organ,  the  sporangium,  con- 


174  YEASTS  AND  MOULDS 

taining  spores  that  become  free  upon  its  rupture.  Or  the 
hyphse  may  split  into  segments,  giving  off  end-pieces  as 
reproducing  elements,  called  conidia,  the  whole  giving  the 
appearance  of  the  hand  bones,  the  phalanges  representing 
the  conidia  (see  Penicillium  glaucum). 

These  moulds  enter  by  wounds,  cracks,  or  hair  follicles, 
and  develop  in  the  superficial  layers  of  the  skin.  The 
mechanical  irritation  set  up  by  their  presence  is  largely 
responsible  for  the  various  diseases  they  occasion .  To  be  sure, 


FIG.  55. — Penicillium  glaucum.   Gelatin  culture.   Spread  stained  with 
gentian  violet.     500  to  1.     (From  Itzerott  and  Niemann.) 

they  can  form  enzymes,  but  of  what  importance  they  are  in 
human  lesions  is  not  known.  The  diseases  are  not  highly 
contagious,  but  of  great  tenacity  when  once  well  advanced. 
Infective  material  comes  away  in  all  cases  with  discharges, 
and  should  be  burned.  Their  principal  diseases  in  the  human 
being  are  as  follows : 

Ringworm. — Of  this  there  are  two  varieties — ringworm 
of  the  skin,  Tinea  circinata,  and  ringworm  of  the  hairy 
portions,  Tinea  tonsurans  or  Tinea  sycosis.  This  is  due  to 
the  Trichophyton  of  various  species,  depending  upon  the  size 


MOULDS 


175 


of  the  spores.  It  is  commonest  in  children  in  schools,  and 
appears  also  where  uncleanliness  prevails,  as  evidenced  by 
epidemics  from  a  badly  kept  barber  shop.  The  fundus 
grows  into  the  hair  sheath  and  inflames  its  base.  The  dis- 
ease appears  characteristically  as  circular,  scaly  patches, 
which  are  rapidly  denuded  of  hair.  This  disease,  so  far  as 
known,  is  only  transmitted  from  man  to  man. 


FIG.  56. — These  two  half-plates  show  three  months'  growth  on  peptone- 
maltose  agar  of  two  megalosporon  varieties  of  the  ringworm  fungus.  Natural 
size.  (Park.) 

Favus. — This  disease  is  caused  by  a  mould  called  Achorion 
Schonleinii,  and  affects  chiefly  the  hairy  portions  of  the 
body.  Animajs  as  well  as  man  are  affected,  and  while  it  is 


176 


YEASTS  AND  MOULDS 


usually  transmitted  from  person  to  person,  either  directly 
or  by  use  of  toilet  articles,  it  is  not  uncommonly  contracted 
by  fondling  affected  cats  and  dogs.  Debilitated  persons  are 
most  susceptible.  The  fungus  penetrates  the  hair  shaft, 
sets  up  a  little  inflammation  which  slowly  spreads,  and  is 
soon  covered  wdth  a  curious  sulphur-yellow  concave  crust 
called  a  scutulum.  The  place  becomes  bald  because  the 
nutrition  of  the  hair  is  cut  off.  Some  cases  are  on  record 
where  this  fungus  has  spread  to  all  the  tissues  of  the  body, 
doing  damage  by  the  irritation  of  its  presence. 


FIG.  57  — Achorion  Schonleinii.     (Flugge.) 

Thrash. — Thrush  or  soor  is  a  disease  caused  by  the  O'idium 
albicans,  and  is  characterized  by  the  presence  of  small  white 
patches  on  the  mucous  membrane,  usually  of  the  mouth, 
in  unclean  or  illy  nourished  children.  It  may  be  found  in 
the  vagina.  It  has  been  known  to  spread  throughout  the 
body. 


MOULDS 


177 


Pityriasis  Versicolor — This  is  a  disease  chiefly  of  unclean 
persons  produced  by  the  development  of  Microsporon  furfur 
in  the  superficial  layers  of  the  epithelium.  It  may  appear 
anywhere 'on  the  body,  but  chiefly  affects  the  short-haired 
skin.  It  is  very  slightly  contagious. 


0 


FIG.  58. — Oidium  albicans:  g,  conidia;  e,  pus  cells, 
and  Wassermann.) 


(From  Plaut,  in  Kolle 


Diagnosis. — The  diagnosis  of  these  conditions  depends 
upon  finding  the  particular  fungus.  Some  of  the  pus  from  a 
blastomycotic  abscess  or  some  of  the  scales  from  the  under- 
side of  the  crusts  of  the  skin  diseases  produced  by  moulds 
is  softened  in  weak  caustic  and  examined  in  a  moist  condition 
under  the  microscope.  The  single  or  budding  cells  of  the 
yeasts  or  the  branching  mycelia  of  the  moulds  are  usually 
found  with  ease.  In  case  it  is  desirable  to  cultivate  the  fungi 
a  long  elaborate  technic  is  necessary. 
12 


CHAPTER  XIII. 
BACTERIA  IN  AIR,  SOIL,  WATER  AND  MILK. 

BACTERIA  IN  AIR. 

THE  bacteria  naturally  found  in  air  are  not  pathogenic, 
but  consist  usually  of  spore  formers  and  moulds;  in  other 
words,  those  having  some  resistance  to  dryness  and  sunlight. 
There  are  more  in  the  layers  of  the  atmosphere  near  the 
earth,  circulating  in  air  currents  after  being  raised  in  dust. 
When  there  are  no  currents,  bacteria  tend  to  settle  on  sur- 
faces, as  they  are  heavier  than  air.  After  rain  storms  the 
atmosphere  may  be  nearly  free  of  organisms.  More  patUo 
genie  forms  are  found  where  people  live  or  congregate,  so 
that  air  currents  produced  by  human  activities  tend  to 
increase  the  bacteria  floating  about.  Colon  bacilli  are 
sometimes  found  in  the  air  above  streets.  Organisms  may 
be  carried  in  currents  set  up  by  coughing  or  blowing.  This  is 
well  shown  by  the  fact  that  tubercle  bacilli  have  been  found 
at  a  distance  of  twenty  feet  in  front  of  a  coughing  consump- 
tive. No  organisms  are  expelled  by  quiet  respiration.  The 
practical  application  of  this  principle  is  the  use  of  moisture 
in  dusting  or  sweeping.  Surfaces  of  a  sick-room  should  be 
wiped  with  a  moist  cloth,  preferably  using  a  disinfectant 
that  will  not  hurt  the  hands.  Bacteria  have  no  power  to 
leave  a  moist  surface.  They  may  be  freed  by  the  bursting 
of  bubbles  of  sputum  or  other  infective  fluid.  They  do  not 
travel  far  by  this  means  if  air  currents  be  absent,  and  there 
is  probably  little  danger  from  simple  unpleasant  odors  from 
drains  if  protected  from  these  currents.  The  only  possible 
danger  from  a  faulty  drain  or  sewer  is  when  obstruction  has 
occurred  and  bubbles  form  from  putrefactions  thus  liberating, 
(178) 


BACTERIA  IN  SOIL  179 

when  they  burst,  some  bacteria  to  be  caught  in  any  air  cur- 
rent that  is  about.  The  danger  is  entirely  theoretical  and 
there  is  no  evidence  that  faulty  drains  produce  disease.  The 
constant  presence  of  a  disagreeable  odor  may  reduce  bodily 
resistance,  that  is  all.  It  is,  however,  more  likely  that  if  a 
householder  allow  a  drain  to  be  faulty  the  general  family 
hygiene  is  poor.  Bacteria  are  found  in  air  by  filtering  a 
definite  quantity  of  air  through  cotton  or  sugar.  The  former 
is  washed,  the  latter  dissolved  in  sterile  water,  and  this  is 
examined  as  outlined  under  water. 

BACTERIA  IN  SOIL. 

Microorganisms  live  in  the  first  few  feet  of  the  earth 
wherever  moisture  and  a  small  amount  of  nourishment  are 
found.  Pathogenic  forms  are  near  the  surface,  while  deeper 
in  pure  saprophytes  are  found.  Bacteria  are  deposited  from 
dust,  water,  and  the  dejecta  of  animals.  Pathogenic  ones 
are  only  to  be  found  where  animal  life  exists,  while  in  unin- 
habited or  untilled  lands  they  probably  do  not  exist  at  all. 
The  denser  the  population  the  more  disease-producing  kinds 
are  found.  Rain  will  wash  away  soil  and  carry  with  it 
bacteria  into  water-courses.  This  is  of  great  importance 
where  human  dejecta  are  deposited  on  the  ground,  but  since 
public  health  authorities  have  now  control  of  the  disposal 
of  wastes,  the  soil  has  become  a  negligible  feature  in  the 
transmission  of  all  but  a  few  diseases. 

Typhoid  fever  epidemics  have  been  known  to  have  such 
an  origin.  Typhoid  germs  can  live  in  soil  for  many  months. 
Vegetables  are  easily  contaminated,  and  if  eaten  raw  can 
transmit  the  disease.  Cholera  vibrios  have  a  shorter  life 
in  this  place.  Anthrax  bacilli  live  a  long  time  and  cattle  are 
sometimes  infected  by  their  pasture.  Actinomycosis  is  well 
known  to  spread  through  a  herd  because  of  infected  pasture 
land.  The  bacteria  of  soil  are  found  by  planting  some  of  it 
in  laboratory  media,  placing  a  part  at  ordinary  temperature 
and  another  at  body  temperature.  By  the  latter  means  the 


180     BACTERIA   IN  AIR,  SOIL,   WATER  AND  MILK 

forms  parasitic  to  animals  are  found.  Tetanus  bacilli  are, 
perhaps,  the  most  widespread  of  pathogenic  bacteria  in  the 
soil.  Their  resistant  spores  remain  alive  an  unlimited  time. 
Persons  going  barefoot  and  subject  to  wounds  or  bruises  may 
contract  the  disease.  Tubercle  bacilli,  in  dead  persons,  live 
only  a  few  months,  but  when  contained  in  sputum  spat  upon 
the  earth  survive  for  a  long  period.  The  important  condi- 
tions in  which  microorganisms  in  the  soil  play  a  part  are 
gas  bacillus  infection,  tetanus,  anthrax  and  uncinariasis, 
hookworm  disease. 

BACTERIA  IN  WATER. 

in  water  there  are  many  hundreds  of  species,  but  it  may 
be  said  in  general  that  all  the  disease-producing  kinds  are 
in  water  because  discharges  from  human  disease  have  been 
put  into  it.  Of  course  this  may  not  be  direct,  but  through 
the  agency  of  soil  as  mentioned  above.  Some  bacteria  may 
be  carried  into  streams  by  rain  which  brings  down  the  dust. 
Rain  itself  is  free  of  germs.  Bacteria  may  be  present  in  water 
up  to  the  billions  without  altering  greatly  its  clearness  or 
giving  it  an  odor,  while,  on  the  other  hand,  a  cloudy  water 
does  not  necessarily  indicate  bacterial  pollution,  for  the 
turbidity  may  be  due  to  harmless  inorganic  chemical  matter. 
Of  the  two  water  sources  recognized  by  hygienists,  ground 
water  (deep  wells)  and  surface  water  (ponds,  lakes,  and  rivers) 
the  second  is  by  far  the  more  important  and  the  more  easily 
polluted.  Large  bodies  of  water,  either  still  or  moving,  tend 
to  rid  themselves  of  bacteria.  In  still  or  slowly  moving 
bodies,  such  as  reservoirs,  germs  settle  with  other  organic 
and  inorganic  matters.  For  water-courses  of  any  character 
purification  is  aided  by  changes  in  temperature  during  the 
day  and  night  and  the  very  efficient  disinfecting  properties 
of  direct  sunlight.  Oxygen  absorbed  from  the  air  also  assists 
in  destroying  bacteria.  There  are  certain  saprophytes  in 
water  and  sewage  capable  of  breaking  up  organic  matter 
and  freeing  oxygen,  which,  either  free  or  in  going  into  com- 


BACTERIA  IN  WATER  181 

bination  with  other  elements  in  chemical  union,  is  inimical 
to  pathogenic  non-spore-forming  bacteria. 

In  this  book  a  word  may  be  useful  as  to  the  means  of 
artificially  purifying  water  for  domestic  purposes.  For  the 
community  water  is  purified  by  settling  in  reservoirs,  or  by 
filtration  through  sand  and  stones,  sometimes  aided  by  the 
addition  of  chemicals.  For  household  purposes  bacteria  in 
water  may  be  removed  by  house  filters  made  of  porcelain 
attached  to  the  house  supply,  or  what  is  better,  .by  boiling. 
Domestic  filters  must  be  taken  care  of  by  some  one  thor- 
oughly familiar  with  their  operation  and  cleaning,  otherwise 
they  do  not  deliver  safe  water.  The  flat  taste  of  boiled  water 
may  be  removed  by  allowing  air  to  go  through  by  pouring 
from  one  container  to  another  several  times. 

Water  in  a  shallow  vessel,  preferably  of  copper,  will  be 
practically  sterilized  by  an  hour's  exposure  to  direct  sunlight. 
This  is  practicable  for  camping  parties  who  are  compelled 
to  use  water  under  suspicion.  Drinking  water  for  companies 
of  troops  on  march  is  supplied  by  filling  a  large  canvas  bag 
with  any  reasonably  good  looking  water  and  adding  calcium 
hypochlorite.  This  ensures,  after  standing  a  short  time,  a 
supply  free  of  organisms  dangerous  to  man.  Canteens  are 
filled  from  faucets  on  the  bag. 

Principal  Water-borne  Diseases. — The  principal  diseases 
transmitted  by  water  are  typhoid,  cholera,  and  dysentery. 
Typhoid  bacilli  may  live  in  water,  especially  if  surrounded 
by  a  bit  of  protective  and  nutrient  organic  matter,  for  many 
weeks.  The  question  is  often  asked  as  to  how  a  few  germs 
in  a  glass  or  two  of  water  can  cause  typhoid  fever.  As  a 
matter  of  fact,  when  an  epidemic  of  typhoid  is  starting  there 
are  usually  supposed  to  be  many  germs  and  not  a  few  in  the 
water.  What  probably  happens  is  that  a  small  particle  of 
organic  matter,  possibly  feces,  is  swallowed.  This  may 
contain  many  thousand  organisms. 

Although  cholera  organisms  live  in  water  a  shorter  time 
than  typhoid  bacilli,  they  are  said  to  be  viable  for  several 


182     BACTERIA  IN  AIR,  SOIL,  WATER  AND  MILK 

weeks.  Relatively  more  cholera  organisms  are  discharged 
with  a  cholera  stool  than  is  the  case  of  typhoid  bacilli  in 
enteric  fever.  Dysentery  bacilli  live  only  a  short  time  in 
water  probably,  and  the  importance  of  water  in  the  dissemi- 
nation of  dysentery  is  questioned  by  some  observers.  Certain 
it  is  that  some  epidemics  appear  to  be  water-borne. 

Typhoid  and  colon  bacilli  are  always  present  in  typhoid 
stools.  It  is  hardly  probable  that  the  former  could  get  into 
water  without  the  latter.  Moreover,  the  colon  bacillus  is 
present  in  all  alimentary  tracts.  It  is  more  easily  detected 
in  any  mixture  or  solution  than  any  other  of  the  intestinal 
bacteria.  Therefore,  it  is  taken  as  an  indication  of  sewage 
pollution  in  water.  This  may  not  mean  that  typhoid  bacilli 
are  present,  but  merely  that  contamination  of  water  by 
sewage  from  animal  sources  has  occurred.  Whether  from 
man  or  animals,  it  is  obvious  that  dejecta  should  not  come 
into  water  intended  for  human  consumption.  The  methods 
of  water  examination  now  in  use  all  aim  at  the  detection  of 
Bacillus  coli.  Because  of  its  peculiarities  in  the  fermenta- 
tion of  sugars,  certain  media  are  adopted  as  standards  for 
its  isolation.  Water  is  carefully  collected  and  kept  upon  ice 
so  that  no  increase  of  bacteria  will  occur.  In  the  laboratory 
suitable  measures  are  taken  to  determine  the  whole  number 
of  bacteria  and  the  presence  of  the  colon  bacillus.  The 
whole  number  is  estimated  by  growing  the  water  in  flat 
plates  of  agar  jelly  and  counting  the  number  of  colonies 
growing  in  forty-eight  hours.  It  is  assumed  that  each  colony 
grows  from  a  single  bacterium.  Chemical  examination  of 
water  aims  at  the  determination  of  the  quantity  of  organic 
matter  indicative  of  sewage  pollution.  Standards  have  been 
set  by  sanitarians,  but  they  are  not  necessary  here. 

BACTERIA  IN  MILK. 

Milk  in  the  deeper  parts  of  the  udder  of  the  healthy  cow 
is  probably  wholly  free  from  bacteria.  The  ducts  of  the 


BACTERIA  IN  MILK  183 

teats,  however,  are  almost  never  free  from  some  germs,  and 
of  course  the  outside  skin  contains  many.  In  a  diseased 
udder  there  may  be  not  only  the  germ  causing  the  disease, 
but  other  intruders  from  the  outside.  Bacteria  come  into 
milk  from  the  cow  herself  or  from  the  outside.  The  latter  is 
probably  the  more  important  and  the  factors  which  must 
be  considered  are  the  dirt  on  the  skin,  swishing  of  the  soiled 
tail,  the  soiled  hands  of  the  dairyman,  and  the  cans,  con- 
taminated by  manure  or  by  polluted  water.  The  ordinary 
milk  bacteria  are  fortunately  not  pathogenic,  the  dangerous 
varieties  from  the  cow  being  only  streptococci  from  inflam- 
mation of  the  udder,  and  tubercle  bacilli.  Those  forms 
getting  into  milk  from  the  surroundings  in  the  dairy  are  only 
important  in  causing  souring  of  the  product. 

Milk  is  a  capital  culture  medium  for  almost  all  bacteria, 
and  as  it  is  warm  when  drawn,  growth  may  begin  shortly. 
Unless  the  milk  be  cooled  very  soon,  to  a  temperature  at 
which  bacterial  growth  is  retarded  or  stopped,  souring  will 
occur.  Perfectly  fresh  milk  has  a  very  slight  restraining 
influence  upon  the  development  of  some  feebler  bacteria, 
but  this  power  is  soon  lost  and  bacterial  growth  may  be 
unlimited.  It  is  best  to  keep  milk  not  above  40°  F.  or  5°  C., 
but  so  low  a  temperature  is  not  always  possible  to  maintain. 
The  consumer  should  strive  to  keep  milk  at  the  lowest  tem- 
perature practicable.  Cities  are  now  controlling  their  milk 
supply  by  various  regulations  as  to  the  dairy  management 
and  shipping  systems.  The  most  important  domestic  means 
of  having  clean  milk  consists  in  receiving  it  in  perfectly 
clean  bottles  and  keeping  it  on  ice. 

Pasteurization. — On  account  of  the  lack  of  perfect  municipal 
control  of  the. milk  supply,  it  is  necessary  to  resort  to  Pas- 
teurization. This  consists  in  heating  the  milk  to  60°  or  70° 
C.,  140°  to  158°  F.,  for  ten  to  twenty  minutes,  and  then 
cooling  rapidly.  Various  methods  are  in  use  commercially, 
but  this  can  be  done  very  easily  in  the  home,  using  a  double 
boiler  and  a  thermometer.  Pasteurization  kills  all  but  the 


184     BACTERIA  IN  AIR,  SOIL,   WATER  AND  MILK 

spores  of  putrefactive  bacteria,  which  are  of  little  danger  if 
the  milk  be  kept  on  the  ice  or  used  shortly.  Some  persons 
object  to  the  use  of  this  heating  because  the  food  value  of 
the  milk  is  reduced  by  making  certain  chemical  constituents 
harder  to  digest.  The  casein  curds-  of  milk  become  tougher 
after  boiling.  There  seems  to  be  no  proof  for  the  statement 
made  in  certain  quarters  that  Pasteurization  causes  the 
elaboration  of  poisonous  substances  in  milk.  Indeed,  some 
pediatrists  are  now  using  boiled  cows'  milk  for  certain  intes- 
tinal disorders  of  children.  If  properly  carried  out,  Pas- 
teurization does  more  good  than  harm,  and  has  proved  its 
value  by  the  reduction  of  the  death-rate  from  infantile  diar- 
rhea in  summer  time.  The  greatest  objection  anyone  can 
raise  to  Pasteurization  is  that  it  gives  a  false  sense  of  security. 
It  cannot  be  too  strongly  emphasized  that  any  natural  anti- 
bacterial power  possessed  by  the  raw  milk  or  the  restraining 
influence  of  lactic  acid  bacilli  on  putrefactive  bacteria  is 
destroyed  by  Pasteurization  and  that  rigid  precautions 
should  be  observed  that  the  heated  milk  is  not  allowed  to 
remain  at  a  temperature  permitting  the  growth  of  bacteria. 
If  kept  below  60°  F.  and  used  within  twenty-four  hours  the 
consumer  is  probably  safe  at  all  times. 

Spoiling  of  Milk. — In  the  summer  conditions  for  the  spoil- 
ing of  milk  are  more  favorable  than  in  winter,  since  the  tem- 
perature is  unfavorable  for  its  preservation,  and  more  dust 
and  flies  introduce  bacteria.  Bottles  in  which  milk  is  served 
should  be  washed  when  empty,  with  cold  water  first,  and  then 
boiled  or  well  scalded.  If  a  small  quantity  of  milk  remain 
in  the  bottom,  putrefactive  and  fermentative  bacteria  grow 
and  dry  on  the  bottle,  making  it  harder  to  clean  subsequently. 
Milk  bottles  should  be  considered  as  possible  carriers  of  dis- 
ease and  the  user  should  assume  his  part  of  the  responsibility 
by  cleaning  them  out  and  not  leave  it  entirely  to  the  milkman. 
The  author  knows  of  one  instance  where  a  milk  bottle  was 
used  as  a  spittoon. 


BACTERIA  IN  MILK  185 

Souring  of  Milk. — The  souring  of  milk  is  due  to  a  variety 
of  bacteria,  chief  among  which  is  Bacterium  lactis  aerogenes, 
related  to  the  Bacterium  bulgaricum  described  above.  This 
germ  is  ubiquitous.  It  is  not  pathogenic.  It  produces  a 
fermentation  of  the  sugar  of  milk,  lactose,  into  lactic  acid. 
Moulds  may  help  this  and  oftentimes  lactic  acid  and  ethyl 
alcohol  may  be  formed  side  by  side.  The  latter  predominates 
in  the  carbonated  milks  like  koumyss.  Other  bacteria  cause 
clot,  or  precipitation  of  the  casein,  the  forerunner  of  cheese. 
Streptococci  from  the  udder  or  manure  may  also  help  in 
souring. 

To  make  buttermilk  in  the  home  is  a  simple  matter.  A 
quantity  of  whole  or  skim  milk  is  boiled  and  cooled.  A 
tablet  containing  the  lactic  acid  bacilli,  a  small  quantity 
of  pure  culture  of  the  organism,  or  a  "starter"  from  a  pre- 
vious making  is  then  added  to  this  cooled  milk  and  set  aside 
in  a  warm  room  (about  75°  F.)  overnight.  The  result  is  a 
rather  agreeable  sour  milk.  Pharmaceutical  chemists  and 
laboratories  are  now  supplying  tablets  and  cultures  for  this 
purpose.  (See  page  166.) 

Diseases  Caused  by  Polluted  Milk. — Many  diseases  are 
believed  to  be  due  to  bad  or  polluted  milk.  If  milk  merely 
carry  the  germs  this  is  easily  understood,  but,  as  is  the  case 
in  the  diarrheas  of  infants,  the  trouble  may  lie  not  with  the 
bacteria  introduced  with  the  milk,  but  with  the  disturbance 
of  digestion  caused  by  the  abnormal  chemical  conditions 
brought  about  by  souring.  These  strange  chemical  sub- 
stances so  prevent  normal  digestion  that  really  pathogenic 
bacteria,  the  dysentery  bacillus  group,  for  example,  are  able 
to  exert  their  noxious  effects.  Streptococci  commonly  present 
in  the  teats,  identical  with  the  Streptococcus  pyogenes,  are 
said  by  some  to  take  advantage  of  this  disturbed  digestion. 
The  examination  for  streptococci  consists  in  simple  staining 
and  finding  of  them  lying  in  or  about  pus  cells.  Health 
authorities  have  rules  covering  this  method  of  examination 
and  the  interpretation  of  results. 


186      BACTERIA  IN  AIR,  SOIL,  WATER  AND  MILK 

Scarlet  fever,  although  its  cause  is  unknown,  is  known  to 
spread  along  milk  routes  and  has  at  times  been  traced  to  a 
case  on  a  dairy  farm.  Foot-and-mouth  disease  of  cattle, 
another  condition  of  unknown  etiology,  has  been  found  in 
children  drinking  milk  from  affected  cows.  The  bacillus  of 
diphtheria  may  live  in  milk  a  long  time  and  may  be  carried 
along  a  milk  route.  It  is  said  that  cholera  may  be  trans- 
mitted by  milk  contaminated  with  polluted  water. 

Typhoid  Fever. — Typhoid  fever  may  be  transmitted  by 
milk  when  a  case  exists  on  a  dairy  farm  or  a  dairyman  uses 
polluted  water  to  wash  his  cans.  In  perfectly  fresh  milk  the 
germs  do  not  thrive,  although  they  are  not  destroyed,  but 
when  a  little  older  the  milk  offers  no  resistance  to  their 
multiplication.  If  sour,  the  lactic  acid  and  alcohol  not  only 
inhibit  their  growth,  but  actually  kill  them.  It  is  frequently 
in  the  period  from  cooling  to  distribution  and  use  that  con- 
tamination occurs.  This  is  done  by  the  hands  of  dairymen, 
shippers,  tasters  (dipping  the  finger  into  the  milk),  or  by 
domestic  servants.  Carriers  of  typhoid  bacilli  are  a  prolific 
source  of  epidemic  spread  by  milk.  One  of  the  carriers  men- 
tioned on  page  110  went  to  work  on  the  dairy  farm  of  her 
brother  immediately  after  the  death  of  her  husband.  In 
three  weeks  twenty-eight  cases  of  typhoid  broke  out  on  the 
farm  and  among  those  using  its  milk.  Although  some  sani- 
tarians discredit  the  milk  transmission  of  typhoid,  the 
following  observation  is  very  significant  when  taken  together 
with  the  fact  that  the  Bacillus  typhosus  has  been  found  in 
milk.  There  is  a  relatively  greater  number  of  women  and 
children  affected  in  milk-borne  epidemics,  while  in  water  and 
general  epidemics  more  men  are  affected.  Pasteurization 
easily  kills  the  typhoid  bacillus. 

Tuberculosis. — The  question  of  the  transmission  of  tuber- 
culosis by  milk  is  one  that  has  raised  much  discussion,  since 
Koch  said  that  the  bovine  type  of  bacillus  does  not  produce 
tuberculosis  in  human  beings.  The  matter  seems  settled 
now  that  tuberculosis  in  the  young  may  be  caused  by  the 


BACTERIA  IN  MILK  187 

bovine  bacillus,  and  is  most  commonly  located  in  the  cervical 
and  abdominal  glands  and  in  the  meninges.  If  a  cow  has 
tuberculosis  of  the  udder,  tubercle  bacilli  are  usually  found 
in  great  numbers  in  the  milk.  If  she  has  lesions  elsewhere 
she  may  still  excrete  the  bacilli  in  the  milk,  but  it  is  impos- 
sible to  determine  when  or  in  what  numbers.  The  obvious 
indication  is  not  to  use  milk  from  a  tuberculous  animal. 
Tuberculin  tests  are  now  being  required  almost  everywhere 
when  permission  to  register  a  milch  cow  is  asked.  No  cow 
giving  a  tuberculin  test  should  be  used  for  a  milk  supply. 
Bacilli  are  also  excreted  in  feces  of  infected  animals,  and  are 
easily  carried  into  the  milkings  by  the  swishing  tail.  Tubercle 
bacilli  of  human  sources  may,  of  course,  be  in  milk  if  handled 
by  a  consumptive.  Pasteurization  does  not  surely  kill  the 
tubercle  bacillus,  especially  if  surrounded  by  a  bit  of  mucus. 

Septic  sore-throat  is  an  epidemic  condition  due  to  strepto- 
cocci of  human  origin  that  get  into  the  milk  by  handling  or, 
quite  as  often  if  not  more  so,  from  the  cow.  While  the  strepto- 
cocci concerned  are  not  pathogenic  for  the  cow,  they  get  into 
the  udder  or  teat  ducts,  live  there  without  causing  inflamma- 
tion but  pass  out  to  be  distributed  with  the  milk.  The  dis- 
ease may  be  very  severe,  be  gravely  complicated  and  at 
times  has  a  considerable  mortality  among  feeble  children 
and  old  persons.  It  seems  not  to  be  easily  transmitted  from 
person  to  person. 

Examination  of  Milk. — Milk  is  examined  for  the  presence 
of  colon  bacilli,  and  the  whole  number  of  bacteria  just  as  in 
the  case  of  water.  For  the  demonstration  of  tubercle  bacilli 
by  stain  a  special  technic  is  necessary.  We  usually  inject 
some  of  the  milk,  cream,  or  sediment  into  guinea-pigs,  and 
expect  lesions  in  them.  The  chemical  examination  of  milk 
usually  shows  its  food  value,  which  may  be  affected  by 
bacteria. 


CHAPTER  XIV. 
DISEASES  DUE  TO  PROTOZOA. 

THERE  are  not  many  recognized  specific  diseases  in  man 
due  to  these  lowest  animal  forms,  but  those  well  known  are 
of  the  greatest  importance,  because  of  their  prevalence  in 
some  parts  of  the  world  and  on  account  of  the  difficulties 
presented  to  medical  treatment.  It  may  be  said  in  general 
that  the  protozoan  diseases  of  man  represent  a  phase  in  the 
life  history  of  the  causative  microorganism,  and  are  in  fact 
stages  through  which  the  protozoa  pass  in  order  to  fulfil  their 
cycle  of  life.  The  subject  of  protozoology  is  of  enormous 
magnitude,  and  it  is  impossible  even  to  outline  in  a  work  like 
this  all  the  steps  which  may  be  passed  through.  An  attempt 
will,  therefore,  be  made  to  describe  the  important  diseases 
due  to  protozoa,  with  a  general  statement  covering  the  mor- 
phology and  life  history  of  the  organism.  Of  the  many 
thousands  of  species  in  nature  only  a  handful  are  pathogenic 
for  man.  The  disease-producing  types  fall  into  the  following 
zoological  families  or  genera:  Sarcodina  (rhizopoda,  amebse) 
Mastigophora  (flagellata,  trypanosoma),  Infusoria  Hetero- 
tricha  (balantidium),  Sporozoa  (coccidia,  hemosporidia, 
plasmodium).  The  diseases,  we  shall  see,  all  fall  into  these 
groups.  They  are  for  the  most  part  dependent  upon  the 
animal  body  for  the  continuance  of  their  life.  Other  forms 
live  in  water,  earth,  decaying  matter,  or  as  apparently  harm- 
less commensal  species  within  the  intestinal  tract  of  animals 
from  insects  up. 

SARCODINA. 

Amebic  Dysentery.— Amebic  dysentery  is  a  subacute  or 
chronic  inflammatory  disease  of  the  large  intestine,  caused 
by  the  Entameba  histolytica  or  dysenteric  ameba.  Contami- 

(188) 


SARCODINA  189 

nated  drinking  water  is  the  most  important  factor  in  the 
transmission  of  the  ameba,  but  soiled  food  and  objects,  hand 
to  mouth  transfer  and  flies  are  not  to  be  ignored  as  probable 
vectors  of  the  parasite.  The  cells  multiply  in  the  small 
intestine,  pass  downward,  and  penetrate  the  mucous  mem- 
brane of  the  colon,  where  in  the  deeper  layers  they  set  up  the 
inflammation  largely  by  their  presence,  but  also  by  some 
soluble  excretory  substance.  From  here  they  may  be  carried 
throughout  the  body,  and  give  rise  to  abscesses,  notably  in 
,the  liver.  These  are  of  long  standing,  and  may  present  work 
for  surgical  interference. 


FIG.  59. — Entameba  histolytica  (Schaudirm)  from  the  stool  of  a  dysentry 
patient.  The  same  individual  showing  two  successive  movements.  The 
nucleus  contains  the  nucleus  and  three  red  blood  cells.  Enlarged  500  to  1. 
(After  Jurgens,  from  Kisskalt  and  Hartmann.) 

The  protozoa  leave  the  body  with  the  feces,  which  to  be 
disinfected  must  be  well  treated  with  carbolic  acid  or  burned, 
the  procedure  being  continued  until  the  feces  are  shown  to  be 
free  of  the  amebse.  They  should  never  be  allowed  to  dry, 
because  the  entameba  may  become  more  resistant  in  a  dry 
state,  due  to  a  curious  spore-like  stage.  This  disease  is 
diagnosticated  by  finding  the  parasites  in  the  feces  or  pus, 
which  must  be  kept  at  a  proper  temperature  during  the 
examination.  Some  of  the  material  is  examined  on  a  warmed 
plate  and  kept  not  lower  than  77°  F.  all  the  time.  At  this 
degree  the  peculiar  movements  of  the  amebse  are  noted  as  a 


190        DISEASES  DUE  TO  PROTOZOA 

pushing  out  of  a  part  of  the  cell  wall  like  a  bud;  this  is  the 
pseudo-pod  or  false  foot.  This  means  of  progression  enables 
the  organism  to  penetrate  intact  mucous  surfaces  and  pass 
through  sand  filters  impermeable  for  bacteria. 

The  Entameba  histolytica  is  an  irregularly  shaped  mass  of 
simple  protoplasm  with  a  primitive  structure.  Its  nucleus 
is  usually  single  in  contrast  to  other  amebse.  It  measures  up 
to  g-J-Q  inch.  It  moves  and  embraces  its  food  by  the  pseudo- 
pods.  It  reproduces  by  division  or  by  the  production  of 
daughter  cells  within  its  body.  When  these  are  massed 
together  and  held  by  a  capsule,  it  is  said  to  be  encysted. 
When  such  cysts  are  taken  into  the  body  the  intestinal  juices 
probably  dissolve  the  capsule  and  let  the  cells  go  free.  Encyst- 
ment  occurs  when  conditions  for  life  become  unfavorable. 
Amebse  are  not  killed  by  cold,  but  succumb  to  60°  C.  or  140° 
F.  in  one  hour.  Acids  are  unfavorable  for  the  growth.  They 
are  cultivated  artificially  with  great  difficulty,  and  are  usually 
combined  with  bacteria,  in  whose  presence  they  multiply 
without  hindrance.  Only  monkeys  and  dogs  are  susceptible 
to  the  amebse  causing  disease  in  man.  No  therapy  depending 
on  antitoxins  or  vaccines  is  practicable. 

MASTIGOPHORA. 

Kala-azar. — In  the  next  group  of  protozoa,  the  flagellata, 
several  are  pathogenic  for  man.  Kala-azar  is  a  peculiar, 
slow  disease,  called  by  various  names,  depending  upon  its 
locality — dumdum  fever,  kala-azar,  etc. — exhibiting  a  large 
spleen,  hemorrhages,  anemia,  and  fever.  The  causative 
microorganism  may  be  found  almost  anywhere  in  the  body, 
but  chiefly  in  the  spleen,  whence  it  may  be  obtained  by 
puncture  with  a  needle.  It  is  said  that  fleas,  bed-bugs  and 
mosquitoes  transmit  the  disease.  The  protozoon  responsible, 
Leishmania  Donovani,  is  an  ovoid  or  circular  or  comma- like 
mass  with  two  nuclei,  and  one  moderately  long  flagellum  on 
the  forward  end.  They  are  from  TT^  or  to  suW  inch  long 
and  about  two- thirds  as  wide.  (See  Fig.  60.) 


MASTIGOPHORA 


191 


Trypanosomiasis. — The  next  flagellate  to  cause  disease  is 
the  Trypanosoma,  two  species  of  which  are  pathogenic  for 
man,  causing  a  disease  called  trypanosomiasis,  or  sleeping 
sickness.  This  affection  is  commonest  in  Africa,  because  of 
the  prevalence  of  the  tsetse  fly,  in  whose  body  the  protozoa 
are  transmitted.  The  bite  of  these  flies  becomes  infective  for 
the  well  three  days  after  biting  the  affected,  and  continues 
so  for  about  four  or  five  weeks.  These  pests  bite  during  the 


.r* 


'  •      «  ^^^^F*.       *         , 

•S^SfSP*4  $V  \i  • 
^^JflifOiV  »•'•' 

SflSfw   - 


S  i  I  *•     '  j 

iT-r.cC 
.  .",";->^'; 

^•^_!^^^    .A 


*t" 


r*K 


^ 


FIG.  60.  —  Protozoa  in  a  case  of  tropical  ulcer. 
(After  Wright.) 


X   1500  approximately. 


daytime,  so  that  protection  and  screening  of  houses  is  insuf- 
ficient usually  to  guard  against  disease.  Inasmuch  as  it  is 
thought  that  some  species  of  trypanosomas  in  the  blood  of 
the  lower  animals  are  infective  for  man,  strict  quarantine  is 
placed  on  animals  within  countries  where  this  disease  exists, 
and  upon  exported  specimens. 

When  the  protozoa  come  into  the  blood  they  are  carried 
throughout  the  body  and  lodge  chiefly  in  the  lymph  glands, 


192  DISEASES  DUE  TO  PROTOZOA 

an  enlargement  of  which  is  an  early  sign  of  infection.  When 
the  disease  is  well  settled  we  see  progressive  anemia,  weakness, 
and  sleepiness,  whence  comes  the  name  " sleeping  sickness." 
The  end  comes  from  profound  anemia  and  prostration. 
Pains  and  dropsical  collections  are  common.  The  disease 
lasts  a  varying  time.  The  early  stages  are  slow,  but  when  the 
great  depression  begins  it  usually  progresses  rapidly  to  a  fatal 
end.  The  changes  produced  are  those  of  obstruction  to  the 


FIG.  61. — Trypanosoma  gambiense.     (From  Calkins.     Preparation  by 
F.  W.  Balstack.) 

lymphatic  system  and  low-grade  chronic  inflammations.  The 
microorganisms  are  present  in  the  blood,  all  organs,  including 
the  lymph  glands,  and  the  cerebrospinal  fluid.  From  all 
these  places  they  may  be  recovered  in  making  a  diagnosis. 
Trypanosomas  are  irregular,  elongated,  twisted  bodies  with 
a  large  nucleus  variously  placed,  and  a  thickened  ribbon- 
like  edge,  the  undulating  membrane,  which  starts  as  a  minute 
secondary  nucleus  at  the  hind  extremity  and  ends  in  a  rather 
long  whip-like  flagellum  at  the  fore  end.  They  range  from 


MASTIGOPHORA 


193 


inch  to  gib  mcn  m  length  and  are  about  J-^O-Q  inch 
wide.  They  move  by  a  sinuous,  jerking,  boring  action. 
Division  takes  place  by  longitudinal  splitting,  probably 
beginning  at  the  hind  end  and  proceeding  along  the  undu- 
lating membrane.  The  true  nucleus  shows  its  division  late. 
The  human  trypanosoma  has  resisted  artificial  cultivation 
until  very  recently,  and  at  the  present  time  it  is  very  difficult 
to  cause  development  in  the  laboratory.  Other  forms  of 
these  protozoa  have  been  grown  with  comparative  ease. 
Most  animals  may  be  the  hosts  of  trypanosoma;  in  some  there 
will  be  disease,  in  others  the  organisms  live  as  harmless 


FIG.  62. — Trichomonas  vaginalis. 
(BlochmaDn.) 


FIG.  63. — Lamblia  intestinalis. 
(Schewiakoff.) 


commensals.  The  modern  treatment  consists  in  using  an 
arsenic -preparation  called  atoxyl.  Numerous  attempts  have 
been  made  to  produce  a  serum  by  injecting  animals  with 
trypanosoma.  Sera  thus  obtained  have  a  slight  beneficial 
effect  upon  the  lower  animals,  but  have  not  proved  of  great 
value  with  human  beings.  The  injection  of  attenuated 
cultures  has  raised  the  resistance  of  certain  lower  animals. 
The  fact  that  some  resistance  can  be  attained  by  attempts 
toward  the  production  of  active  and  passive  immunity  indi- 
cates that  trypanosoma  exert  their  action  by  some  poison. 
Whether  it  be  in  their  bodies  or  elaborated  in  the  juices 
about  them  is  not  known. 
13 


194         DISEASES  DUE  TO  PROTOZOA 

Trichomonas. — Two  protozoa  of  a  slight  medical  impor- 
tance are  the  Trichomonas  vaginalis,  with  its  nearly  related 
varieties,  T.  intestinalis  and  T.  pulmonalis,  and  the  Lamblia 
intestinalis.  These  forms  may  infest  the  vagina,  intestine, 
or  lung,  and  cause  some  irritation,  probably  not  particularly 
inflammatory.  They  are  held  responsible  oftentimes  for  the 
inflammation  set  up  by  bacteria  gaining  entrance  at  the  site 
of  the  irritation  by  the  protozoa.  However,  the  vaginitis 
and  cystitis  caused  by  the  T.  vaginalis  are  serious  matters 
in  children.  These  are  usually  pear-shaped  bodies,  with 
prominent  nucleus  and  well-marked  anterior  flagella.  The 
trichomonas  has  a  heavy  undulating  membrane. 


FIG.  64. — Some  of  the  principal  forms  assumed  by  the  plasmodium  of 
tertian  fever  in  the  course  of  its  cycle  of  development.  (After  Thayer  and 
Hewetson.) 


SPOROZOA. 

Malaria. — The  most  important  disease  caused  by  protozoa 
is  malaria.  This  is  an  infectious  disease  characterized  by 
intermittent  chills,  fever,  and  sweats,  with  prostration  and 
progressive  anemia.  It  is  common  in  lowlands,  where 
stagnant  water  collects,  or  in  the  vicinity  of  slowly  moving 
water,  permitting  the  propagation  of  mosquitoes.  "It  is  not 
communicable  by  contact  of  man  to  man.  It  is  the  infesta- 
tion of  the  red  blood  cells  by  a  parasite  having  three  forms, 


SPOROZOA  195 

belonging  to  the  order  Hemosporidia.  The  parasites  are 
called  the  Plasmodium  vivax,  the  P.  malaria,  and  the  P. 
falciparum.  Three  types  of  attack  correspond  to  the  three 
protozoal  species:  (1)  That  which  gives  chills  and  fever 
every  third  day,  the  tertian  malaria;  (2)  one  where  the 
paroxysm  appears  every  fourth  day,  the  quartan  type,  and 
(3)  a  continuous,  typhoid-like  type,  the  malignant  or  estivo- 
autumnal  fever. 

The  species  vary  in  finer  morphological  details,  but  they 
follow  the  same  course  in  their  transmission  and  develop- 
ment in  regard  to  infectivity,  except  that  they  require  differ- 
ent times  for  their  full  development. 


•   a  b 

FIG.  65. — Egg  of  Culex  (a)  laid  together  in  "small  boat;"  those  of  Anopheles 
(6)  separate  and  rounded.     (From  Kolle  and  Hetsch.) 

The  female  mosquitoes  of  the  genus  Anopheles  carry  the 
disease  from  one  person  to  another.  They  fly  and  bite  in  the 
early  evening.  These  mosquitoes  may  be  recognized  by  their 
position  on  a  surface.  Their  body  forms  a  large  angle  with 
the  surface,  and  the  head  is  on  a  line  with  the  body.  The 
ordinary  mosquito,  Culex,  stands  parallel  with  the  surface 
with  the  head  bent  down.  Furthermore,  the  wings  of  the 
Anopheles  are  furred  on  the  flat  surface,  while  the  Culex 
wings  are  only  fitted  with  widely  set,  fine  hairs  on  the  edges. 
There  are  many  other  differences,  but  these  will  suffice  as 
general  guides.  The  female  mosquito  bites  a  malarial  person 
and  receives  the  parasites  into  her  stomach.  Here  they 
undergo  reproduction  by  a  sexual  process,  and  appear  in  her 
salivary  gland  in  a  condition  ready  for  transmission  to  the 
next  person  bitten.  This  gland  is  connected  with  the  biting 


196 


DISEASES  DUE  TO  PROTOZOA 


apparatus,  and  some  of  its  secretion  is  left  under  the  skin 
when  the  mosquito  bites  and  sucks  blood.  It  is  probably  the 
secretion  from  this  gland  which  causes  the  itching  of  the 


FIG.  66.— Larva  of  Culex  (a)  hangs  nearly  at  right  angles  to  water  surface; 
those  of  Anopheles  (6)  are  parallel  to  the  surface.     (From  Kolle  and  Hetsch.) 


FIG.  67. — Body  of  Culex  (a)  when  resting  is  held  parallel  to  wall  in  a 
curved  position,  that  of  Anopheles  (6)  at  an  angle  of  about  45  degrees  and 
is  straight;  wings  of  Culex  (c)  are  generally  not  spotted;  those  of  Anopheles 
(d)  are  spotted.  (From  Kolle  and  Hetsch.) 

ordinary  mosquito  bite.  This  reproduction  in  the  mosquito 
requires  seven  to  ten  days.  When  a  person  is  bitten  the 
parasites,  left  under  the  skin,  penetrate  their  cell  of  choice, 
the  red  blood  corpuscle.  In  the  body  of  this  cell  they  have 


SPOROZOA 


197 


the  power  of  undergoing  an  asexual  division  (see  Fig.  64). 
The  minute  form  swells  into  a  large  body  and  breaks  up  into 
small  spores.  When  this  mass  of  young  forms  has  reached  a 
size  too  great  for  the  red  cell  the  latter  bursts,  synchronously 
with  which  we  have  the  chill.  By  this  bursting  young  forms 
are  again  set  free  in  the  blood,  each  capable  of  entering  other 
red  blood  cells.  Of  course,  not  all  the  cells  are  affected,  but 
in  severe  cases  one  of  every  thirty  red  blood  cells  may  con- 
tain the  parasites,  but  as  the  disease  progresses  and  succes- 


FIG.  68. — In  Culex  the  palpae  (a)  of  the  female  are  very  short,  of  the  male 
are  longer  than  the  proboscis;  in  Anopheles  the  palpse  (6)  of  both  sexes  are 
about  equal  in  length  with  the  proboscis.  (From  Kolle  and  Hetsch.) 

sive  crops  of  corpuscles  are  destroyed  the  sum  total  of  the 
damage  may  be  great.  As  a  result  of  this,  severe  grades  of 
anemia  result.  The  cycle  of  development  from  the  young 
form  to  the  bursting  requires  forty-eight  hours  for  the 
tertian  malaria  and  seventy-two  hours  for  quartan  malaria, 
while  in  estivo-autumnal  malaria  there  is  a  slowly  progres- 
sive attack  on  successive  cells  by  a  curious  extracellular  and 
irrtracellular  crescent-shaped  body. 
The  anatomy  of  these  plasmodia  is  of  great  intricacy,  and 


198  DISEASES  DUE  TO  PROTOZOA 

undergoes  so  many  changes  that  it  is  hardly  desirable  to  go 
into  detail  here.  Suffice  it  to  say  that  it  is  a  body  when 
adult  somewhat  larger  than  a  red  blood  cell,  full  of  actively 
moving  granules.  The  young  forms  are  homogeneous,  and 
are  found  with  the  greatest  difficulty  except  when  specially 
stained.  They  probably  get  all  their  granules  from  the 
destruction  of  the  red  blood  cells.  Some  adult  forms  have 
flagella  about  their  wall.  The  power  of  producing  disease 
lies  partly  in  their  destruction  of  the  important  cells  of  the 
blood  and  partly  in  a  poison  they  produce.  The  internal 
organs,  especially  the  spleen,  are  injured  first  by  the  damage 
of  the  blood,  and  secondarily  by  the  extra  work  thrown  on 
them  in  trying  to  destroy  the  parasites  and  to  remove  the 
pigment  which  is  liberated  by  the  cellular  disintegration. 
A  slight  immunity  remains  after  an  attack.  There  is  a  rela- 
tive racial  immunity  among  the  negroes.  The  cases  that 
do  not  wholly  recover  or  that  have  remote  recurrences  are 
said  to  be  harboring  quiescent  parasites  in  the  spleen.  A 
chronic  inflammation  of  this  organ  often  results. 

Diagnosis. — The  disease  is  diagnosticated  by  making  fresh 
or  dried  and  stained  preparations  of  the  blood  and  examining 
them  under  the  microscope.  Should  malaria  organisms  be 
present,  faint,  irregular  shadows  or  larger  bodies  filled  with 
dancing  granules  are  seen  in  the  unstained  blood,  while  in 
stained  smears  fairly  well-colored  parasites  containing  quiet 
granules  will  be  found.  Animals  are  not  susceptible  to  human 
malaria.  Monkeys  may  be  artificially  infected.  No  anti- 
serum  or  vaccine  treatment  is  possible  now.  Quinine  is  a 
specific,  and  if  properly  used  will  cure  all  cases.  The  spread 
of  malaria  is  checked  by  preventing  the  propagation  of  mos- 
quitoes. These  insects  lay  their  eggs  on  the  surface  of  quiet 
water.  The  young  remain  at  the  surface  of  the  water  when 
they  require  air.  Oil  is  spread  upon  the  surface  of  the  water 
and  all  marshes  are  drained.  No  increase  of  the  insects  can 
go  on  if  these  two  things  are  done.  No  quarantine  of  the 
patient  other  than  screening  from  mosquitoes  is  necessary. 


CHAPTER  XV. 
DISEASES  OF  UNKNOWN  ETIOLOGY. 

WHILE  this  book  concerns  itself  with  the  relation  of  micro- 
organisms to  disease,  it  is  fitting  that  mention  be  made  of 
some  communicable  affections,  in  which  the  causative  agent 
is  not  yet  known.  The  clinical  observations  upon  these 
infections  indicate  that  they  are  due  to  some  form  of  living 
body  which  present  methods  of  investigation  do  not  permit 
us  to  demonstrate.  It  is  inconceivable  that  so  specific  a 
condition  as  smallpox  should  come  from  anything  but  a 
self-reproducing  agent.  Nevertheless  the  viruses  of  these 
diseases  must  be,  at  least  in  some  part  of  their  existence,  very 
tiny,  because  they  are  able  to  pass  through  the  pores  of  a 
porcelain  filter  that  would  hold  back  bacteria.  For  this 
reason  the  following  diseases  are  said  to  be  due  to  "filterable 
viruses."  We  may  later  learn  to  know  the  agents  as  physical 
entities,  but  those  which  can  be  cultivated  now  are  only 
imperfectly  understood. 

Smallpox  or  Variola. — This  is  an  acute  infectious  disease 
characterized  by  severe  constitutional  symptoms  and  a  rash 
which  becomes  pustular,  leaving  behind  it  after  recovery 
peculiar  depressed  scars.  It  is  believed  today  that  the  various 
affections  of  man,  cow,  horse,  and  sheep  are  practically 
identical.  Certain  it  is  that  infection  with  cowpox  will  give 
resistance  to  human  smallpox.  Vaccination  was  formerly 
practised  by  transferring  the  pox  from  person  to  person,  but 
now  fresh  material  is  used  from  a  cow  which  has  been  arti- 
ficially infected  with  smallpox.  By  passing  this  virus  through 
the  calf  it  is  so  altered  that  it  cannot  produce  smallpox  in 
man,  yet  it  can,  when  inoculated  into  the  skin,  call  forth  an 

(199) 


200  DISEASES  OF  UNKNOWN  ETIOLOGY 

immunity  against  subsequent  infection  with  that  disease. 
Jenner,  in  1798,  was  the  one  who  first  developed  the  principle 
of  using  cowpox  in  the  protection  against  human  variola. 
The  exact  cause  of  smallpox  is  not  known.  It  is  supposed  to 
spread  by  contact  either  directly  with  the  sick  or  indirectly 
by  objects  having  been  in  contact  with  them.  Such  objects 
are  called  fomites.  Bacteria  are  present  in  the  pustules 
caused  by  vaccination  and  in  the  eruption  of  smallpox,  but 
they  have  been  proved  to  be  secondary  invaders.  The  virus 
is  in  the  eruption  or  the  scales  and  all  discharges  from  the 
body  which  should  therefore  be  disinfected. 

Varicella  or  Chicken-pox.  —  This  is  one  of  the  eruptive 
infections  characterized  by  moderate  fever  and  catarrhal 
symptoms,  but  especially  by  a  papular  rash  which  becomes 
vesicular  then  pustular,  only  to  dry  up  and  disappear  rapidly. 
The  condition  is  of  trifling  moment  and  leaves  no  serious 
sequelae;  occasionally  shallow  pock  marks  remain.  The 
cause  is  unknown  but  probably  is  present  in  the  skin  lesions 
only  early  in  the  eruption  and  passes  directly  from  person  to 
person  by  freshly  contaminated  articles.  Patients  should 
be  kept  away  from  non-immunes  until  all  eruption  has 
disappeared.  It  is  only  necessary  to  disinfect  discharges 
from  lesions  and  nasal  and  buccal  secretions. 

Rabies  or  Hydrophobia. — This  is  an  acute  infectious  disease 
to  which  nearly  all  animals  are  susceptible,  characterized 
by  slowly  progressive  palsies  and  delirium.  Hydrophobia 
means  fear  of  water.  Such  an  emotion  does  not  exist,  but 
animals  merely  avoid  water  because  they  cannot  swallow  it. 
The  cause  of  rabies  is  excreted  in  the  saliva  and  may  be  trans- 
mitted by  the  bite  of  a  rabid  animal,  or  by  getting  the  saliva 
into  an  open  wound.  The  virus  is  innocuous  if  swallowed. 
After  having  entered  the  body  the  virus  travels  to  the  central 
nervous  system  and  remains  there  throughout  the  whole 
attack.  The  spinal  cord  particularly  is  involved.  The  only 
evidence  there  is  of  the  actual  causative  germ  is  the  presence 
of  minute  stainable  granules  in  the  nerve  cells  of  the  brain. 


RABIES  OR  HYDROPHOBIA  201 

These  so-called  "Negri  bodies"  are  demonstrated  by  special 
staining  methods.  When  a  dog  is  suspected  he  is  killed  and 
his  brain  removed.  Bits  of  it  are  stained  for  microscopic 
examination  and  other  pieces  are  made  into  an  emulsion, 
which  is  injected  into  the  brain  of  a  rabbit.  If  rabies  virus 
be  present,  this  susceptible  animal  will  die  within  three  weeks 
as  a  rule.  Recently  attempts  at  the  cultivation  of  the  rabies 
virus  have  been  rewarded  by  the  development,  under  anaero- 
bic conditions,  of  minute  globoid  bodies  writh  a  tiny  iwo'eus 
and  with  such  cultures  animals  have  been  infected. 

Pasteur  found  a  method  for  protective  inoculation  treat- 
ment against  rabies.  He  found  that  if  the  spinal  cord  of  a 
rabbit  suffering  from  rabies  wrere  removed  and  dried  in  a 
vacuum  it  lost  its  virulence  for  other  rabbits.  If  he  dried  it 
twro  weeks  nearly  all  of  the  virulence  was  lost,  but  if  only 
two  days,  its  strength  was  only  slightly  impaired.  He  found 
that  if  he  inoculated  animals  with  gradually  increasing 
strengths  or  quantities  of  emulsions  made  from  these  dried 
rabbits'  spinal  cords,  a  certain  degree  of  immunity  was 
obtained.  This  principle  is  now  used  in  treating  persons 
bitten  by  rabid -animals.  The  treatment  is  possible  after  the 
bite  and  the  outlook  is  better  the  sooner  after  infection  the 
treatment  is  begun.  The  spinal  cords  of  rabbits  are  ground 
up  in  glycerin  and  injections  are  made  under  the  skin.  The 
patient  first  receives  a  dose  from  a  cord  dried  fourteen  days, 
then  from  one  dried  twelve  or  thirteen  days,  then  ten  or 
eleven. days,  and  so  on  until  one  dried  two  days  is  used.  The 
mortality  from  rabies  has  been  greatly  reduced  by  this 
method  of  active  immunization.  At  present  there  is  no  very 
accurate  laboratory  diagnostic  test  in  rabies.  The  develop- 
ment of  the  symptoms  must  be  awaited  to  make  the  diag- 
nosis in  people  bitten  by  rabid  animals,  but  preventive 
measures  take  the  form  of  ascertaining  that  the  dog  has 
rabies,  using  the  Pasteur  treatment  and  cauterizing  the 
wound.  The  ordinary  disinfecting  dressings  of  bichloride  of 
mercury  and  carbolic  acid  solutions  are  worthless  for  the 


202  DISEASES  OF  UNKNOWN  ETIOLOGY 

bites  of  rabid  animals.  It  is  necessary  to  use  the  actual 
cautery  or  fuming  nitric  acid  in  order  to  certainly  remove 
rabies  virus  from  a  wound. 

Yellow  Fever. — This  is  an  acute  infectious  disease  chiefly 
of  tropical  countries,  characterized  by  great  prostration, 
severe  pains,  hemorrhages,  and  jaundice.  The  cause  is  not 
known,  but  lately  Noguchi  has  discovered  a  minute  spiro- 
chete  with  which  it  seems  possible  to  reproduce  the  infection 
in  animals.  The  disease  is  transmitted  by  the  mosquito  called 
Aedes  calopus,  which  takes  some  of  the  infective  blood  from 
a  patient  and  transmits  it  to  another  person.  The  virus  is 
in  the  patient's  blood  in  a  condition  in  which  the  mosquito 
can  take  it  during  only  the  first  three  days  of  fever.  Some 
cycle  of  development  of  the  virus  takes  place  in  the  mosquito 
because  the  insect  is  only  capable  of  depositing  it  in  a  bite 
when  twelve  days  shall  have  elapsed  since  it  bit  a  yellow- 
fever  patient.  More  than  that,  five  days  elapses  between  the 
bite  of  the  mosquito  and  the  appearance  of  the  virus  in  the 
patient's  blood.  Because  of  these  facts  the  modern  concep- 
tion of  yellow  fever  supposes  a  protozoon  as  the  cause.  There 
are  no  laboratory  diagnostic  measures  nor  as  yet  any  specific 
treatment.  The  spread  of  yellow  fever  is  prevented  by 
destroying  the  breeding  places  of  the  mosquito,  a  difficult 
thing,  since  this  insect  breeds  in  lowlands  and  bushes  and  in 
houses.  It  bites  usually  in  the  late  afternoon. 

Typhus  Fever. — Although  this  condition  is  not  understood 
clearly,  it  now  seems  that  body  lice,  flies,  and  ticks  transmit 
it.  It  is  a  filterable  virus  also  and  can  be  transmitted  to 
monkeys.  A  bacterium  has  lately  been  found,  however, 
which  in  certain  ways  seems  to  have  something  to  do  with 
the  disease.  Typhus  fever  exists  in  America  in  a  mild  form 
known  as  Brill's  disease. 

Scarlet  Fever. — This  is  variously  ascribed  to  protozoa  and 
to  streptococci;  neither  claim  is  well  supported.  The  virus 
is  in  the  blood  and  can  be  transmitted  to  monkeys  at  the 
height  of  the  attack;  in  these  animals  a  fever  occurs,  but  no 


POLIOM  YELITIS  203 

disease  typical  of  scarlatina.    The  virus  may  be  also  in  the 
peeling  skin. 

Measles. — As  in  the  former  disease  various  microorganisms 
have  been  held  responsible  but  no  certain  one  can  be  con- 
victed. The  virus  in  the  blood  of  patients,  in  their  nasal  and 
buccal  secretions,  and  when  any  of  these  are  transferred  to  a* 
monkey  a  fever  quite  like  that  of  the  human  disease  will 
develop.  The  viruses  of  both  diseases  are  filterable. 

German  Measles. — This  is  a  mild  infection  transmitted  by 
secretions  of  the  nose  and  throat,  which  should  be  disinfected. 

The  last  three  diseases  form  the  bulk  of  the  infections  of 
early  life.  They  are  comparable  in  being  easily  transmitted 
and  almost  exclusively  by  direct  personal  contact  or  by 
contact  with  objects  freshly  soiled  with  secretions  from  the 
nose  and  throat.  Their  period  of  infectivity  is  from  just 
before  the  onset  until  the  catarrhal  lesions  of  the  upper  air 
passages  have  disappeared.  Fortunately  the  viruses  are 
easily  destroyed  by  the  usual  disinfectants. 

Poliomyelitis. — This  is  an  acute  apparently  infectious  dis- 
ease characterized  by  a  mild  constitutional  illness  followed 
by  gradually  appearing  and  progressing  paralyses.  It  may 
be  sporadic  or  appear  in  epidemics.  The  infective  agent  and 
its  mode  of  transmission  are  not  known.  It  probably  enters 
by  the  nose  and  throat.  The  virus  is  present  in  the  feces, 
blood,  lymph  glands,  and  especially  in  the  central  nervous 
system.  It  is  so  small  that  it  will  pass  through  porcelain 
filters  such  as  are  used  for  water  purification.  The  disease 
may  be  reproduced  in  monkeys  by  injecting  this  virus  by 
almost  any  route,  and  it  is  strictly  comparable  to  that  seen 
in  human  beings.  It  is  not  known  how  the  virus  leaves  the 
body,  but  as  the  nose  and  throat  seem  the  most  likely  places, 
they  should  be  disinfected  in  both  frank  and  mild  ambulant 
cases  and  in  attendants  by  the  use  of  hydrogen  peroxide 
solution.  On  account  of  the  otherwise  inexplicable  transfer 
of  the  disease  to  new  places  it  is  supposed  that  healthy  per- 
sons carry  the  infection  probably  in  the  nose  and  throat.  A 


204  DISEASES  OF  UNKNOWN  ETIOLOGY 

case  is  probably  infectious  for  three  weeks  after  onset,  so 
that  disinfecting  measures  should  be  continued  for  that 
period.  There  is  reason  to  believe  that  cases  are  infectious 
before  the  disease  becomes  recognizable,  thus  making  an  epi- 
demic difficult  to  control.  There  is  as  yet  no  reliable  specific 
treatment.  The  only  laboratory  test  consists  in  finding  in  the 
cerebrospinal  fluid  an  excess  of  a  certain  organic  substance 
called  globulin  and  a  very  small  increase  of  cells. 

Mumps. — This  is  an  acute  inflammatory  infectious  disease 
of  the  salivary  glands,  the  cause  of  which  is  not  known.  It 
is  disseminated  by  direct  contact,  and  the  virus  is  in  the 
saliva. 

Other  Diseases. — Other  diseases  which  human  beings  may 
contract  due  to  invisible  viruses,  are  foot-and-mouth  disease 
of  cattle,  dengue,  beriberi,  and  pellagra.  Nearly  all  of  these 
viruses  are  small  enough  to  go  through  a  porcelain  filter.  It 
may  be  said  in  general  that  to  protect  one's  self  from  the 
infection  the  local  lesions  and  skin  eruptions  should  be 
disinfected. 

Acute  Articular  Rheumatism. — The  modern  conception  of 
this  disease  is  that  it  is  an  acute  infection.  Many  bacteria 
have  been  described  as  its  cause,  but  their  defenders  have  not 
built  up  unanswerable  arguments  in  their  support.  The 
theory  now  holding  the  stage  is  that  a  streptococcus  called 
Streptococcus  rheumaticus  enters  by  the  tonsils,  penetrates  to 
the  blood  stream,  and  settles  in  the  joints.  Certain  it  is  that 
we  frequently  have  streptococcus  sore-throat  associated  with 
acute  rheumatism,  and  that  the  inflammations  of  the  heart 
lining  after  this  disease  are  frequently  streptococcal. 

Impetigo  Contagiosa. — This  is  an  acute  pustular  eruption 
of  the  skin,  thought,  but  not  proved,  to  be  due  to  the  pus 
cocci.  Some  observers  maintain  that  a  protozoon  is  the  cause. 
At  all  events  pus  cocci,  both  streptococci  and  staphylococci, 
are  present.  The  lesions  are  at  first  pustules,  but  soon  break 
down  to  flat  ulcers.  They  occur  chiefly  upon  the  face.  The 
disease  is  transmitted  by  direct  intimate  contact,  such  as 


TRENCH  FEVER  205 

kissing.  Mild  antiseptics  are  sufficient:  1  to  1000  carbolic 
acid  or  1  to  3000  corrosive  sublimate.  A  salve  of  mercury  is 
usually  prescribed.  Its  importance  is  greatest  in  surgical 
and  children's  wards  and  clinics  and  in  schools. 

Noma  or  Cancrum  Oris. — This  is  a  perforating  ulceration, 
usually  of  the  cheek,  on  weak  and  debilitated  children.  It  is 
said  to  be  due  to  a  host  of  different  organisms,  cocci,  pseudo- 
diphtheria  bacilli,  and  many  others.  The  one  most  frequently 
found  is  an  anaerobic  germ  of  double  appearance,  as  a  rod 
and  as  a  spirochete.  The  treatment  is  of  a  radical  surgical 
character,  as  ordinary  external  applications  are  unavailing. 
It  is  not  very  contagious,  but  discharges  and  sloughs  are  best 
burned. 

Trench  Fever. — Trench  fever  is  an  infectious  disease  of 
primarily  acute  nature,  but  occasionally  assuming  a  subacute 
or  chronic  form.  It  is  characterized  by  irregular  fever, 
vertigo,  severe  headache  and  bone  pains  and  sweating  and 
evidences  of  blood  infection.  It  is  transmitted  by  the  body 
louse  and  possibly  by  other  parasites.  The  lice  bite  infected 
persons,  the  virus  being  in  the  blood,  and  act  as  hosts  for  it 
because  it  requires  seven  days  for  the  development  within 
the  body  of  the  parasite.  The  lice  do  not  then  transmit  the 
virus  by  biting  or  at  least  not  only  in  that  manner,  as  it  seems 
that  the  deposition  of  excreta  of  the  louse  upon  the  skin  is 
sufficient  for  the  non-immune  to  be  infected.  The  lice 
remain  infective  for  at  least  three  weeks  but  do  not  pass  the 
virus  to  their  young.  Disinfection  takes  the  form  of  destroy- 
ing lice  and  nits,  for  which  kerosene,  cresol,  and  hot  soap 
water  are  used.  The  clothing  must  be  rendered  innocuous 
by  steam  or  soaking  in  a  proper  solution. 


GLOSSARY. 


THE  meaning  of  many  words  occurring  several  times  in 
the  text  is  given  here  that  the  reader  may  the  more  intelli- 
gently follow  the  subject  matter.  Certain  unusual  terms 
used  seldom  and  sufficiently  explained  under  special  headings 
are  not  repeated  here.  Nearly  all  words  in  scientific  language 
are  derived  from  Latin  or  Greek  roots  and  are  to  be  pro- 
nounced precisely  as  printed. 

Aerobic — Preferring  or  demanding  atmospheric  oxygen  for  life. 

Agglutinins — Substances  in  the  serum  capable  of  clumping 
bacteria.  Related  words:  to  agglutinate,  agglutination. 

Anaerobic — Preferring  or  demanding  the  absence  of  atmospheric 
oxygen  for  life. 

Anaphylaxis — A  condition  of  high  sensitivity  due  to  idiosyncrasy 
to  or  previous  injection  with  certain  organic  substances  but  other- 
wise unexplained  as  yet.  Symptoms:  shortness  of  breath,  skin  irri- 
tations, and  sometimes  death. 

Antibodies — Substances  developed  in  the  blood  serum  which 
neutralize  the  toxins  of  bacteria,  but  this  word  is  usually  used  with 
reference  to  intracellular  toxins. 

Antitoxins — Antibodies  developed  in  the  blood  serum  which 
neutralize  extracellular  toxins  of  bacteria. 

Asexual — Applied  to  forms  that  can  multiply  without  being 
divided  into  two  separate  and  recognizable  sexual  elements. 

Attenuate — To  reduce  in  virulence. 

Bacillus  (pi.,  Bacilli) — The  genus  of  motile  rods  in  the  vegetable 
kingdom. 

Bacteriacese — The  family  of  rod-shaped  bacteria. 
(206) 


GLOSSARY  207 

Bactericide — A  substance  used  to  kill  bacteria;  also  called  a 
"germicide."  Related  word:  bactericidal. 

Bacterins — The  dead  bodies  of  bacteria  used  to  treat  disease  by 
injection  under  the  skin;  also  called  " vaccines." 

Bacteriology — The  study  of  bacteria.    Adj.,  bacteriological. 

Bacteriolysin — An  antibody  that  will  dissolve  bacteria.  Related 
words:  bacteriolysis,  bacteriolytic. 

Bacterium  (pi.,  Bacteria) — From  Greek  word  meaning  little  stick; 
the  genus  of  non-motile  rods.  The  words  are  also  used  to  mean  any 
of  these  lowest  plants. 

Carrier — A  term  applied  to  a  person  who  carries  germs  capable 
of  being  transmitted  to  and  infecting  others,  but  himself  not  neces- 
sarily suffering  at  the  time  from  the  disease  caused  by  the  germ. 

Cell — The  smallest  recognizable  unit  in  biology.  Cells  are  single 
and  independent  in  bacteria  and  protozoa,  but  are  combined  and 
dependent  upon  one  another  in  the  higher  plants  and  animals. 

Coccacese — The  family  of  the  spherical  vegetable  organisms. 

Coccus  (pi.,  Cocci) — A  spherical  organism. 

Colony — The  individual  group  growing  upon  laboratory  food- 
stuffs, and  usually  referring  to  one  small  group.  The  word  is  used 
for  the  growths  upon  flat  dishes  that  are  supposed  to  arise  from  a 
single  organism. 

Commensal — Living  in  harmless  union  either  independently  or 
for  mutual  benefit. 

Complement — A  constituent  of  all  sera  which  helps  in  the  union 
of  antibodies  and  bacteria. 

Cultivation — A  word  used  to  embrace  all  the  procedures  employed 
to  make  germs  grow  under  the  laboratory  conditions. 

Culture — The  mass  of  bacteria  grown  artificially  upon  laboratory 
foodstuffs.  The  general  term  applied  to  the  way  bacteria  grow. 
See  Colony.  Adj.,  cultural. 

Cytoplasm — The  soft  part  of  a  cell  between  the  wall  and  the 
nucleus;  also  called  protoplasm. 

Dejecta — The  feces  and  urine;  also  used  to  mean  sputum,  sweat, 
and  morbid  discharges. 

Disinfection — The  destruction  of  infective  material.  See  p.  50  for 
various  degrees. 


208  GLOSSARY 

Encystment — The  grouping  together  within  a  resistant  membrane 
of  forms  or  stages  in  the  life  cycle  of  organisms,  or  a  resting  stage 
when  conditions  for  life  are  unfavorable. 

Enzyme — The  products  of  life  of  organisms  by  which  they  digest 
their  foodstuffs.  A  substance  capable  of  splitting  others  into  simpler 
ones  without  itself  undergoing  any  change  or  entering  into  the  new 
product.  Also  called  ferment.  Related  words:  enzymic,  enzymatic. 

Etiology — Study  of  the  cause  of  a  disease  and  its  transmission; 
also  the  cause  itself. 

Ferment — (pronounced  fer-ment) — See  Enzyme. 

Fermentation — The  breaking  of  sugars  and  starches  (carbo- 
hydrates) by  bacterial  ferments,  with  the  production  of  carbon 
dioxide,  alcohols,  and  sometimes  acids.  Related  words:  to  ferment, 
fermentative. 

Genus — Next  to  the  lowest  division  of  biological  classification, 
including  members  of  the  lowest  division,  species,  among  which 
there  are  only  slight  differences.  Members  of  a  genus  must  be  alike 
in  all  important  characters.  See  Species. 

Germination — The  progressive  multiplication  of  the  active  adult 
forms. 

Growth — A  word  used  to  cover  the  appearance  of  a  culture  on 
laboratory  media,  and  sometimes  used  interchangeably  with 
culture. 

Host — The  body  which  carries  a  parasite. 

Immunity — The  resistance  of  the  body  to  illness.  See  p.  65  for 
kinds.  Related  words:  to  immunize,  immunization,  immune. 

Infective — Any  material  carrying  disease  viruses. 

Inhibit — Restrain,  limit. 

Inject — To  put  anything  within  the  body;  in  this  book  it  usually 
means  to  put  beneath  the  skin. 

Inoculate — To  put  some  infective  material  within  the  body; 
usually  used  in  experimental  work  upon  lower  animals. 

Inorganic — Of  the  mineral  world  and  not  necessarily  associated 
with  living  matter;  example,  salt.  See  Organic. 

Isolate — Used  to  indicate  the  procuring  of  germs  from  morbid 
fluids  or  to  the  obtaining  of  a  single  kind,  a  pure  culture,  usually 
by  finding  one  type  of  colony.  Related  word :  isolation. 


GLOSSARY  209 

Lesion— Used  to  indicate  any  physical  change  from  normal. 
Leukocytes — The  colorless,  so-called  white  cells  of  the  blood. 

Medium  (pi.,  Media) — General  name  given  to  foodstuffs  upon 
which  bacteria  are  grown  artificially. 

Micrococcus — The  genus  of  spherical  organisms  dividing  in  two 
planes.  , 

Morphology — A  study  of  the  physical  nature,  size,  and  shape  of 
any  object.  Adj.,  morphological. 

Nucleus  (pi.,  Nuclei)— A  mass  within  a  cell  clearly  outlined  from 
and  denser  than  the  cytoplasm  or  protoplasm,  and  in  which  the 
reproductive  powers  of  the  cell  probably  lie. 

_0l0gy_A  suffix  meaning  a  "study  of"  the  root,  such  as  mor- 
phology, which  see. 

Opsonins— Substances  in  the  blood  serum  which  prepare  foreign 
bodies,  usually  bacteria,  for  consumption  by  the  white  cells  of  the 
blood,  the  phagocytes. 

Optimum — The  best,  most  suitable. 

Organic— A  substance  having  the  form,  the  chemistry,  or  some 
characteristics  of  living  matter;  example,  egg  white.  See  Inorganic. 

Parasite— An  organism  living  on  or  in  a  host  to  the  detriment  of 
the  latter.  Adj.,  parasitic. 

Pathogenic — Capable  of  producing  disease. 

Pathology— The  study  of  disease— the  broad  subject  of  the  cause, 
production,  and  result  of  disease,  and  especially  the  changes  it 
produces  in  the  body.  Related  words :  pathologic,  -al. 

Phagocytosis— The  act  of  consuming  foreign  bodies,  notably 
bacteria,  by  the  large  white  cells  of  the  blood,  called  phagocytes. 
Adj.,  phagocytic. 

Plane— The  geometrical  dimension.  There  is  one  plane  in  a  line, 
two  planes  in  a  surface,  and  three  planes  in  a  body,  suoh  as  a  cube. 

Plasma— The  fluid  part  of  the  blood  including  the  constituents 
capable  of  clotting.  See  Serum. 

Poisons— Used  generally  to  indicate  any  substance  dangerous 
to  body.    Has  no  particular  significance  for  bacterial  products  when 
used  alone. 
14 


210  GLOSSARY 

Proliferate — To  multiply,  increase. 

Prophylaxis — Guarding  against  beforehand.  Measures  toward 
preventing  disease.  Adj.,  prophylactic. 

Protoplasm — See  Cytoplasm. 

Protozoa  (sing.,  Protozobn) — The  lowest  order  of  animals,  inde- 
pendent single-celled  organisms. 

Pseudo — False,  resembling. 

Pseudopods — The  foot-like  projections  of  the  cell  wall  and  cyto- 
plasm shown  by  amebae,  a  method  of  progression  for  these  protozoa. 

Putrefaction — The  decaying  of  proteid  (the  large  part  of  meat 
and  fish)  with  the  production  of  foul  odors  and  poisonous  substances. 
(This  is  to  be  contrasted  with  fermentation,  which  see;) 

Pyogenes — Pus-producing.    Adj.,  pyogenic. 

Saprophyte — An  organism  capable  of  living  on  dead  or  decaying 
matter.  Adj.,  saprophytic. 

Serum  (pi.,  Sera) — The  clear  light  yellow  fluid  part  of  the  blood 
which  exudes  after  clotting  has  occurred,  and  in  which  antibodies 
reside. 

Sexual — Requiring  two  different  forms  for  reproduction. 

Species — The  lowest  biological  division  of  living  forms,  varying 
only  in  unimportant  characters,  but  possessing  all  the  characters 
of  the  genus  to  which  they  belong.  Lions  and  tigers  belong  to  the 
genus  Felis  (or  cat),  but  the  former  belongs  to  the  species  "leo," 
and  the  latter  to  the  species  "tigris."  See  Genus 

Spirocheta  (pi.,  Spirochetae)  —  The  spiral  or  corkscrew-like 
organisms;  name  given  both  to  family  and  genus. 

Staphylococcus  — The  spherical  coccus  which  grows  hi  grape-like 
masses. 

Sterile — Bacteriologiaally  speaking,  entirely  free  of  living 
organisms.  A  surgically  sterile  thing  may  contain  organisms  from 
the  air  which  do  not  hurt  the  patient.  Related  words:  sterility, 
sterilization,  to  sterilize. 

Strain — An  individual  culture  of  a  species  isolated  from  a  case. 

Streptococcus — The  spherical  coccus  which  grows  in  chains. 

Toxins — The  poisonous  products  of  bacterial  life. 
Tumefaction— Any  tumor-like  swelling. 


GLOSSARY  211 

Vaccine — Originally  used  for  the  inoculation  of  cowpox  as  a 
protective  agaiAst  smallpox;  now  used  for  that  and  for  the  injection 
of  dead  or  attenuated  bacteria  for  active  immunization  or  treatment 
during  disease.  See  Bacterins.  Related  words:  to  vaccinate, 
vaccination. 

Viable — Capable  of  living  and  reproducing. 

Virulence — The  power  possessed  by  organisms  to  develop  poisons 
and  produce  disease.  It  varies  in  different  strains,  but  depends  also 
upon  the  resistance  of  the  host. 

Virus — Any  factor  which  produces  disease,  either  individually 
recognized  or  obscure;  usually  applied  to  poisons  not  specifically 
isolated,  like  rabies  virus. 


INDEX. 


A 


ABSCESS,  80 

Achorion  Schoenleinii,  175,  176.  See 

Favus. 

Acid-fast  bacilli,  138,  149 
Acids,  53 
Actinpmyces,  154.  See  Streptothrix 

actinomyces. 
Actinomycosis,  154 

bacteriological  diagnosis  of,  156 

disinfection  during  attack  of,  156 

in  soil,  179 

transmission  of,  155 
"  Active  immunization,"  66 
Aedes  calopus,  202 
Aerobe,  206 
Aerobic  bacteria,  33 
Agglutinins,  68,  206 
Air,  bacteria  in,  137,  178 

currents,  178 

examination  of,  for  bacteria,  179 

transmission  of  disease  by,  134, 

178 

Alcohol,  52,  185 
Algae,  21 

Amebae,  189,  190 
Amebic  dysentery,  188 
diagnosis  of,  189 
disinfection  during  attack,  189 
Anaerobe,  206 
Anaerobic  bacteria,  33 
Anaphylaxis,  70,  206 
Animal  inoculation,  42 
Animalculse,  18 
Anthrax,  69,  152 

antiserum,  154 

bacillus,  69,  152 

general  description  of,  153 
pathogenic  powers  of,  152,  154 
poisons  of,  152 
relation  of,  to  anthrax,  152 


Anthrax  bacillus,  resistance  to  heat 

and  chemicals,  54,  154 
in  soil,  179 
vaccines,  154 

bacteriological  diagnosis  of,  153 
disinfection  during  attack  of,  153 
transmission  of,  152,  153 
vaccines,  154 

Antibody,  67  to  69,  206 

Anti-endo toxins,  66 

Antimeningitis  serum,  94 

Antiseptics,  49 

Antiserum,  70,  97 

Antitoxin  unit,  102,  107 

Antitoxins,  67,  102,  107,  206 

Asexual,  206 

Attenuation,  49,  206 

Autoclave,  43,  44 

Auto-intoxication,  35,  166 


B 


BACILLI,  21,  24,  206 
Bacillus  coli  communis,  158.     See 
Colon  bacillus. 

of  Ducrey,  145.     See  Chancroid. 

dysenteriae,    127.      See    Dysen- 
tery bacillus. 

enteritidis,  162 

gas,  167.     See  Bacterium  aero- 
genes  capsulatus. 

of  Koch-Weeks,  131 

melitensis,  117.   See  Malta  fever. 

of  Morax  and  Axenfeld,  132 

paratyphosus,  116 

pestis,  120.    See  Plague  bacillus. 

proteus  vulgaris,  168 

pyocyaneus,  169 

diagnosis   of  infections   with, 

170 

general  description  of,  169 
(213) 


214 


INDEX 


Bacillus    pyocyaneus,    pathogenic 

powers  of,  170 
poisons,  170 

resistance  to  heat  and  chemi- 
cals, 170 
where  found,  169 

tetani,  113.    See  Tetanus  bacil- 
lus. 

typhosus,    104.      See    Typhoid 

bacillus. 
Bacteremia,  60 
Bacteria,  17,  21,  206 

activities  and  nature  of,  32 

aerobic,  33 

anaerobic,  33 

biological  classification  of,  21 

capsule  of,  26 

chemistry  of,  30 

colonies  of,  38 

cultivation  of,  38-39 

cytoplasm  of,  23 

endotoxins  of,  61 

entrance  of,  to  body,  59 

enzymes  of,  34 

extracellular  toxins  of,  61 

in  fermentations,  34 

ferments  of,  34 

flagella  of,  26 

in  hair,  95 

in  intestinal  tract,  32  to  35 

intracellular  toxins  of,  61 

lactic  acid,  34,  166 

motility  of,  26 

nucleus  of,  23 

nutrition  of,  33 

pathogenic,  20 

poisons  of,  60,  61,  62,  67 

in  putrefaction,  34 

relation  of,  to  disease,  59 

reproduction  of,  25 

resistance  of  body  to,  60,  65  to 
68,80 

size  of,  24,  25 

specificity  of,  60 

spores  of,  27 

staining  of,  41 

toxins  of,  61,  66 

transmission  of,  62 

vegetating,  47 

wall  of,  23 
Bacteriacese,  21,  206 
Bactericide,  207 
Bacterin  treatment,  69,  84 
Bacterins,  69,  84,  207 


Bacteriology,  17,  207 
Bacteriolysin,  68,  207 
Bacterium  aerogenes  capsulatus, 

167 

antiserum  for,  167 
anthracis,      152.     See     Anthrax 

bacillus. 

bulgaricum,  166,  167,  185 
diphtherise,  98.    See  Diphtheria 

bacillus, 
influenzae,    117.     See   Influenza 

bacillus. 

lactis  aerogenes,  185 
leprse,  147.    See  Leprosy  bacillus, 
of  malignant  edema,  168 
mallei,  150.    See  Glanders  bacil- 
lus. 

ozenae,  165 

pneumonise,     164.      See    Fried- 
lander's  bacillus, 
tuberculosis,  134.     See  Tubercle 

bacillus. 

Balantidium,  188 
Beriberi,  204 
Bichloride  of  mercury,  50 
Blastomycetes,  21,  172 
diagnosis  of,  177 
disinfection  during  attack,   173 
transmission  of,  172 
Blood  culture  technic,  77 
Boiling  for  sterilization,  46 
Boils,  84 
Books,  disinfection  of,  58 

transmission  of  disease  by,  57 
Bordet-Gengou  bacillus,  133.    See 

Whooping-cough. 
Boric  acid,  53 
Buttermilk,  185 


CALCIUM  hydroxide,  51 

Cancrum  oris,  205 

Capsules,  26 

Carbolic  acid,  52 

Carriers,  64,  99,  110,  124,  207 

accidental,  64 

chronic,  64 

hidden,  64 

infection,  92 

passive,  64 
Caustic  soda,  51 
Cell,  23,  207 


INDEX 


215 


Cellulitis,  80 
Centigrade  scale,  48 
Centrosome,  29 
Cerebrospinal  meningitis,  91 

puncture,  76 
Chancroid,  145 
Chemical  disinfectants,  49  to  54 

practical  uses  of,  55  to  58 
Chemistry  of  bacteria,  30 

of  protozoa.  31 
Chloramin-T,  52 
Chloride  of  lime,  51 
Chlorinated  lime,  51 
Cholera,  123 
agglutination  in,  125 
antiserum,  70 

bacteriological  diagnosis  of,  125 
bacteriolytic  test  for,  125 
disinfection  during  attack,  124 
spirillum,  124,  181 
agglu tinins  of,  125 
carriers  of,  124 
general  description  of,  125 
in  milk,  186 

pathogenic  powers  of,  123,  126 
poisons  of,  123 
relation  of,  to  Asiatic  cholera, 

123 
resistance    of,    to    heat    and 

chemicals,  125,  126 
in  soil,  179 
vaccines,  126 
in  water,  181 
transmission  of,  123 
vaccination  against,  126 
Cilia,  29 
Coccaceae,  207 
Cocci,  21,  24,  207 
Coccidia,  188 
Colon  bacilluF,  82,  158 

diagnosis  of,  infections   with, 

161 

general  description  of,  158,  159 
pathogenic  powers  of,  160 
poisons  of,  160 
resistance    of,    to    heat    and 

chemicals,  159 
use  in  intestines,  159 
vaccines,  161 
in  water,  182 
where  found,  159,  160 
Colonies,  38,  207 
Commensal,  207 
Complement,  68,  207 


Conjunctivitis,  gonorrheal,  88 
Koch- Weeks  (pink-eye),  131 
Morax-Axenfeld,  132 

Copper  sulphate,  51 

Corrosive  sublimate,  50 

Cowpox,  199,  200 

Creolin,  52 

Cresols,  52 

Cultivation,  38,  207 

Culture,  207 

Cytoplasm,  23,  30,  207 


DARIN'S  solution,  51 
Dejecta,  207 
Dengue,  204 

Diarrhea,  infantile,  from  milk,  185 
Dichloramin-T,  52 
Diphtheria,  98 
administration  of   antitoxin  in, 

102 

antitoxins,  102 
bacillus,  61,  64,  98 
antitoxins,  102 
discovery  of,  100,  101 
general  description  of,  100 
in  milk,  186 

pathogenic  powers  cf,  99,  101 
poisons,  61,  102 
relation  of,  to  diphtheria,  98 
resistance    of,    to    heat    and 

chemicals,  100,  101 
bacteriological  diagnosis  of,  100, 

101 

disinfection  during  attack,  99 
Schick  test  in,  103 
serum  sickness  following,  71 
transmission  of,  99,  185 
Diplococci,  24,  26 
Diplococcus  pneumoniae,  95.    See 

Pneumococcus. 
Disease,  59 

transmission  of,  62 
water-borne,  181 
Dishes,  disinfection  of,  47 
Disinfectants,  49 

uses  of,  55  to  58 
Disinfection,  49,  207 
of  dejecta,  56 
practical,  49 
of  room  and  houses,  57 
of  sputum,  56 


216 


INDEX 


Disinfection  of  water-closets  and 

sinks,  57 

Dressings,  disinfection  of,  47 
Dumdum  fever,  190 
Dysentery,  amebic,  127,  188 
bacillary,  127 
antibodies,  129 
antiserum,  70,  129 
bacteriological    diagnosis    of, 

128,  129 

disinfection  during  attack,  128 
transmission  of,  128 
bacillus,  127 
agglutinins,  129 
antisera,  129 
bacteriolysins,  128 
general  description  of,  129 
pathogenic  powers  of,  127,  129 
poisons,  127 

relation  of,  to  dysentery,  127 
resistance    of,    to    heat    and 
chemicals,  129 


ENCYSTMENT,  208 

Endotoxins,  61,  66 

Entameba  histolytica,    189.      See 

Amebic  dysentery, 
general  description  of,  190 
pathogenic  powers  of,  190 
Enteric  fever,  108.     See   Typhoid 

fever. 
Enzymes,  34,  40,  208 

in  industries,  34 
Etiology,  208 
Exudate,  81 

F 

FAHRENHEIT  scale,  48 
False  membrane,  82 
Favus,  175 
Feces,  collection  of,  75 

sterilization  of,  56 
Fermentation,  18,  34,  40,  185,  208 
Ferments,  34,  40,  208 

in  industries,  34 
Fever,  60 

Filterable  viruses,  199 
Flagella,  26,  29 
Flagellata,  188 
Flies  in  transmission  of  disease,  63, 

110 


Flies,  tsetse,  63,  192 
Fomites,  63 
Formaldehyde,  53,  54 
Formalin,  54,  55 
Friedlander's  bacillus,  164 

pathogenic  powers  of,  164 
Fungi,  21 


GAS  bacillus,  167.    See  Bacterium 

aerogenes    capsulatus. 
Gauze  masks,  use  of,  64 
reclamation  of,  58 
sterilization  of,  58 
Generation,  spontaneous,  19 
Genus,  208 
Germination,  208 
Glanders,  150  to  152 
bacillus,  150 

general  description  of,  151 
pathogenic  powers  of,  150 
poisons,  150 

relation  of,  to  glanders,  150 
resistance    of,    to    heat    and 

chemicals,  151,  152 
vaccines,  152 

bacteriological  diagnosis  of,  150 
disinfection  during  attack,  151 
mallein  in,  150 
transmission  of,  150 
vaccines  in,  152 
Glassware,  43 
Glossary,  206 
Gonococcus,  62,  87 
in  conjunctivitis,  88 
general  description  of,  89,  90 
relation  of,  to  gonorrhea,  87 
resistance     of,     to     heat     and 

chemicals,  90,  91 
vulvovaginitis  due  to,  89 
Gonorrhea,  87 

bacteriological  diagnosis  of,  91 
disinfection    during    and    after 

attack,  89 
Gonorrheal  conjunctivitis,  88 

ophthalmia,  88 
Gram  stain,  42 
Growth,  208 


HAIR,  bacteria  in,  99 
Hanging  drop,  40 


INDEX 


217 


Heat  sterilization,  43  to  48 

Hemosporidia,  188,  195 

Heterotricha,  188 

Host,  20,  208 

Hot-air  sterilization,  47 

Hydrophobia,  200 

disinfection  against,  201 
Pasteur  treatment  for,  201 
transmission  of,  200 
virus  of,  200 

Hyphae,  173 

Hyphomycetes,  21,  171 


ICE  and   typhoid  fever  transmis- 
sion, 109 
Ileocolitis,  127 
Immunity,  65  to  72,  208 

acquired,  66 

active,  66,  69 
acquired,  66 

artificial,  66 

natural,  65 

passive,  66 
acquired,  66 

racial,  65 

Impetigo  contagiosa,  204 
Incubation  period,  62 
Incubator,  39 
Infection,  60 

carriers,  92 

Eredisposing  causes  to,  60 
active,  208 
Inflammation,  80 
Influenza,  117,  133 
agglutinins,  119 
bacillus,  62,  91,  117 

general  description  of,  119 
pathogenic  powers  of,  117,  118 
poisons,  117 
relation  of,  to  influenza,  117 

to  other  diseases,  118 
resistance  to  beat  and  chemi- 
cals, 119 
vaccines,  120 

bacteriological  diagnosis  of,  119 
disinfection  during  attack,   119 
immunity  after  attack,   118 
meningitis,  118,  120 
transmission  of,  117 
Infusoria,  188 
Inhibit,  208 


Inject,  208 
Inoculate,  208 
Inorganic,  208 
Insects,  63 
Intoxication,  60 
Iodine,  52 

alcohol,  52,  55 
Isolate,  208 


KALA-AZAR,  190 
Klebs-Lceffler  bacillus,  98 
Kock-Weeks  bacillus,  131,  132 
Koumyss,  166 


LACTIC  acid  bacteria,  34,  166,  185 
Lamblia  intestinalis,  194 
Leishmania  Donovani,  190 
Leprin,  149 
Leprosy,  147  to  149 
bacillus,  147 

general  description  of,  149 
pathogenic  powers  of,  148 
poisons  of,  148 
relation  of,  to  leprosy,  147 
bacteriological  diagnosis  of,  149 
disinfection  during  attack,  149 
forms  of,  147 
transmission  of,  147 
Lesion,  209 

Leukocytes,  69,  80,  81,  209 
Lichens,  21 
Lime,  milk  of,  55 
Lysol,  52 

M 

MALARIA,  63,  194 
diagnosis  of,  198 
estivo-autumnal,  195,  197 
malignant,  195 
prevention  of,  198 
quartan,  195,  197 
tertian,  195,  197 
Mallein,  150 
Malta  fever,  117 
bacilli  in,  117 
general  description  of,  117 
transmission  of,  117 


218 


INDEX 


Masks,  gauze,  use  of,  64 
Mastigophora,  21,  188,  190 
Measles,  203 

Meat  poisoning  bacteria,  162 
Media,  38,  40,  209 
Meningitis,  91 

antiserum  to,  70,  94 

bacteriological  diagnosis  of,  93 

carriers,  64 

coccus,  93,  94 
antiserum,  87 
general  description  of,  94 
relation  of,  to  meningitis,  91 

disinfection  during,  93 

influenzse,  118,  120 
Methods  of  examination,  37 
Microbiology,  17 
Micrococcus,  82,  209 

gonorrhoea,  87.   See  Gonocoecus. 

intracellularis   meningitidis,    91. 

See  Meningitis  coccus. 
Microscope,  23 

technic  of,  23,  40 
Microsporon  furfur,  177 
Milk,  bacteria  in,  182 

cholera  spirilla  in,  186 

collection  of,  77 

diphtheria  bacilli,  186 

diseases  transmitted  by,  62,  117, 
185 

examination  of,  187 

fermentation  of,  184,  185 

infantile  diarrhea  from,  185 

of  lime,  55 

pasteurization  of,  183 

scarlet  fever  from,  186 

souring  of,  185 

spoiling  of,  184 

streptococci,  183 

tubercle  bacilli  in,  183,  186 

typhoid  fever  and  bacilli  in  rela- 
tion to,  186 

Morax-Axenfeld  bacillus,  132 
Morphology,  209 

of  bacteria,  22 

of  protozoa.  29 

variations  of,  24 
Mosquitoes,  anopheles,  63,  195,-  196 

culex,  195,  196 

in  transmission  of  diseases,  63, 

194,  202 
Moulds,  22,  173 

diseases  due  to,  173  to  177 

general  disposition  of,  173  to  175 


Moulds,  pathogenic  powers  of,  174 
Mucosus  capsulatus  group,  163 

general  description  of,  163 

pathogenic  power  of,  163 

poisons,  163 

resistance  of,  to  heat   and 
chemicals,  163 

transmission  of,  164 

vaccines,  165 
Mumps,  204 
Mycelium,  173 


N 

NOMA,  205 
Nucleus,  23,  29,  209 
Nutrition  of  bacteria,  33 
of  protozoa,  35 


OIDIUM  albicans,  176 
Ophthalmia  neonatorum,  88 
Opsonic  index,  84 
Opsonins,  68,  84,  209 
Optimum,  209 
Organic,  209 


PARACOLON  bacilli,  161 
Parasites,  20,  209 

facultative,  20 

obligate,  20 

Paratyphoid  bacilli,  116 
Pasteur  treatment  of  rabies,  201 
Pasteurization,  58,  183,  187 
Pathogenic,  209 
Pathology,  209 
Pellagra,  204 
Penicillium  glaucum,  174 
Phagocytes,  68,  209 
Phagocytosis,  68,  209 
Phenol,  52 
Phlegmon,  80 
Pink  eye,  131 
Pityriasis  versicolor,  177 
Plague,  120 

antiserum,  122 

bacillus,  120 

antisera,  122,  123 


INDEX 


219 


Plague    bacillus,    general  descrip- 
tion of,  122 

pathogenic  power  of,  121 
poisons,  121 

relation  of,  to  plague,  120 
resistance    of,    to    heat    and 

chemicals,  122 
vaccines,  123 

bacteriological  diagnosis  of,  122 
disinfection  during  attack,  121 
immunity  against,  123 
immunization  against,  123 
rat  fleas  in  transmission  of,  121 
rats  in  transmission  of,  121 
transmission  of,  120,  121 
vaccines  in,  123 
Plane,  209 
Plasma,  209 
Plasmodium,  188 
falciparum,  195 
general  description  of,  198 
life  in  mosquitoes,  196 
malaria?,  195 

pathogenic  powers  of,  195  to  197 
vivax,  195 

Pneumococcus,  92,  95 
antiserum,  97 

in    diseases    other    than    pneu- 
monia, 92,  95 
general  description  of,  96 
pathogenic  powers  of,  97 
poisons,  97 

relation  of,  to  pneumonia,  95 
resistance     of,     to     heat     and 

chemicals,  97 
Pneumonia,  95,  164 
antiserum,  70,  97 
bacteriological  diagnosis  of,  95 
disinfection  during,  95 
Poliomyelitis,  203 

virus  of,  203 
Proliferate,  210 
Protoplasm,  210 

Protozoa,  17,  21,  29,  31,  35,  42,  188 
biological   classification    of,    21, 

188,  210 

centrosome  of,  29 
chemistry  of,  31 
cilia  of,  29 
cytoplasm  of,  29 
examination  for,  42 
flagella  of,  29 
morphology  of,  29 
motility  of,  29 


Protozoa,  nucleus  of,  29 

nutrition  of,  30 

pseudopods  of,  30 

reproduction  of,  30 

requirements,  36 

temperature  for,  36 

wall,  29 

Protozoology,  17 
Pseudodiphtheria  bacilli,  104 
Pseudopods,  30,  210 
Ptomain  poisoning,  64 
Pus,  79,  82 

bacillus  of  green,  169 

collection  of,  73 
Putrefaction,  34,  210 
Pyemia,  80 
Pyocyanase,  170 
Pyocyaneus  bacillus,  82,  169 
Pyogenes,  210 


R 


RABIES,  200.    See  Hydrophobia. 

Rain,  bacteria  in,  180 

Ray  fungus,  155.  See  Strepto- 
thrix  actinomyces. 

Reclamation  of  gauze,  58 

Relapsing  fever,  146 

Reproduction,  25,  30 

Rheumatism,  acute  articular,  204 
streptococcus  rheumaticus  in,  204 

Rhizopoda,  188 

Ringworm,  174 

Room  disinfection,  49,  57 

Rubber  gloves,  disinfection  of,  47 

Russell,  Major,  U.  S.  A.,  anti- 
typhoid vaccination,  115 


S 


SAPROPHYTES,  20,  210 

in  intestine,  34 
Sarcinae,  26 
Sarcodina,  21,  188 
Scarlet  fever,  64,  202 

from  milk,  186 

Schick  test  in  diphtheria,  103 
Schizomycetes,  21 
Septic  sore- throat,  86 

tank  process  of  sewage  disposal, 

35 
Septicemia,  60,  80 


220 


INDEX 


Serum,  210 

sickness,  71 

treatment,  70 

Sewage  disposal,  septic  tank  pro- 
cess of,  35 
Sexual,  210 
Silver  nitrate,  50 
Skin  sterilization,  53,  55,  76 
Sleeping  sickness,    63,     192.      See 

Trypanosomiasis. 
Smallpox,  69,  199 
Smegma  bacillus,  149 
Soap  as  disinfectant,  53 
Sodium  carbonate,  51 

hydroxide,  51 
Soil,  179 

actinomycosis  from,  179 

anthrax  bacillus  in,  179 

bacteria  in,  179 

cholera  bacillus  in,  179 

tetanus  bacillus  in,  179 

tubercle  bacillus  in,  180 

typhoid  bacillus  in,  179 
Soor,  176.     See  Thrush. 
Sore-throat,  septic,  86 
Species,  210 
Spirilla,  21,  24 
Spirillum  cholera?  asiaticse,  123.  See 

Cholera  spirillum. 
Spirocheta,  210 

Obermeieri,  146 

pallida,    142.      See    Treponema 

pallidum. 

Spontaneous  generation,  19 
Spores,  27,  46,  47,  51,  52 
Sporozoa,  21,  188,  194 
Sputum,  collection  of,  73 

sterilization  of,  56,  138,  140 

tuberculous,  collection  and  steril- 
ization of,  56,  138 
Staining,  37,  42 
Staphylococci,  26,  82,  210 
Staphylococcus  epidermidis  albus, 
77,  83 

pyogenes  albus,  83 
aureus,  82,  83 
discovery  of,  87 
diseases  produced  by,  84 
general  description  of,  82,  83 
resistance  of,   to  heat  and 

chemicals,  83 
Steam  sterilization,  43,  45,  46,  47 

sterilizer,  45,  46,  47 
Sterilization,  43  to  47,  49  to  54,  210 


Sterilization  of  dejecta,  56 
of  fabrics,  55 
of  glassware,  43 
of  gauze,  58 
hot-air,  47 
incomplete,  49 
of  sputum,  56,  138,  140 
of  utensils,  56 
of  water-closets,  57 
Strain,  210 
Streptococci,  26,  62,  82,  85,    185, 

210 

Streptococcus  pyogenes,  85 
antiserum,  70,  87 
discovery  of,  87 
diseases  due  to,  85 
general  description  of,  86 
rheumaticus,  204 
Streptothrix  actinomyces,  155.    See 

Actinomycosis. 
general  description  of,  156 
pathogenic  powers  of,  155 
poisons,  156 

relation  to  actinomycosis,  155 
resistance    of,    to    heat    and 

chemicals,  156 
Sulphur  dioxide,  53 
Sunlight,  58 
Syphilis,  142  to  146 
antibodies  in,  143 
diagnosis  of,  143 
forms  of,  143 
skin  reaction  in,  145 
transmission  of,  143 
Wassermann  blood  reaction  in, 

143 
Syringes,  disinfection  of,  46 


TECHNIC,  37 

Temperature  optimum,  43 
Tetanus,  70,  104 
antitoxin,  107 

administration  of,  107 
unit  of,  107 
bacillus,  66,  104 
antitoxin,  107 
effect  of  anaerobic  life,  105 
general  description  of,  105 
pathogenic  powers  of,  105 
relation  of,  to  tetanus,  104 
resistance    of,    to    heat    and 
chemicals,  106 


INDEX 


221 


Tetanus  bacillus  in  soil,  179 
spores  of,  106 
toxins  of,  61,  106 
bacteriological  diagnosis  of,  105 
disinfection  during  attack,  105 
Thallophyta,  21 
Thermometer  scales,  48 
Throat,  septic  sore,  86 
Thrush,  176 

Tinea  circinata,    174.     See    Ring- 
worm. 

sycosis,  174.     See  Ringworm, 
tonsurans,  174.    See  Ringworm. 
Toxins,  bacterial,  61,  67,  210 
extracellular,  61 
intracellular,  61 
Transmission  of  bacteria,  62 
of  diseases,  62,  163 

by  books,  57 
Trays,  disinfection  of,  46 
Trench  fever,  205 
Treponema  pallidum,  142 

general  description  of,  144 
pathogenic  powers  of,  142 
poisons,  142 

relation  of,  to  syphilis,  142 
resistance    of,    to    heat    and 

chemicals,  144,  145 
transmission  of,  143 
Trichomonas,  194 
intestinalis,  194 
pulmonalis,  194 
vaginalis,  194 
Trichophyton,  174,  175 
Tricresol,  52 
Trypanosoma,  188,  192 

general  description  of,  192 
pathogenic  powers  of,  192 
Trypanospmiasis,  192 
transmission  of,  192 
Tsetse  fly,  63,  192 
Tubercle  bacillus,  63,  134 
in  air,  178 
forms  of,  137 

general  description  of,  140 
in  milk,  137,  186 
pathogenic  powers  of,  134,  135 
poisons,  139,  141 
relation  of,  to  tuberculosis,  134 

137 
resistance    of,    to    heat    and 

chemicals,  140 
in  soil,  180 
transmission  of,  137 


Tubercle  bacillus  vaccines,  141 
Tubercles,  135 
Tuberculin,  139,  141,  187 
Tuberculosis,  134  to  142 
agglutinins  in,  139 
antibodies  in  blood  in,  136 
bacteriological  diagnosis  of,  138 
from  cows,  141,  186 
disinfection  during  attack,    138 
forms  of,  135 
from  milk,  186 
skin  test  in,  139 
sputum  in,  disinfection  of,  138, 

140 

transmission  of,  137 
tuberculin  reaction  in,  139 

treatment,  141 
vaccines,  141 
Tumefaction,  240 
Typhocolon  group  of  bacilli,   157 

to  163 

discovery  of,  162 
Typhoid  bacillus,  64,  82,  108 
agglutinins,  112 
carriers,  64,  110 
general  description  of,  113,  114 
in  milk,  186 

pathogenic  powers  of,  108,  115 
poisons,  111 

relation  to  typhoid  fever,  108 
resistance  to  heat  and  chemi- 
cals, 114 
in  soil,  179 
vaccines,  115 
in  water,  109,  181 
fever,  108 

antibodies  after  attack,  111 
bacteriological    diagnosis    of, 

112 

bacteriolysins  in,  112 
carriers,  110 
disinfection  during  attack,  1 10 

111 

immunity  after,  111 
immunization  against,  114 
Russell's  vaccination  against, 

result  of,  115 
transmission  of,  109 
by  flies,  110 
by  ice,  109 
by  milk,  109,  186 
by  oysters,  110 
by  personal  contact,  110 
by  sewage,  109 


222 


INDEX 


Typhoid  fever,    transmission    of, 

by  vegetables,  110,  179 
by  water,  109,  181,  182 
Widal  reaction  in,  112 
Typhus  fever,  202 


URINE,  collection  of,  75 
sterilization  of,  56 


VACCINATION,  199 
Vaccine  treatment,  69,  84,  115 
Vaccines,  69,  84,  115,  199,  211 
Variola,   199.     See  Smallpox. 
Vegetables  in  typhoid  fever  trans- 
mission, 110,  179 
Vegetative  bacteria,  28 
Viable,  211 
Vincent's  angina,  130 

bacteriological    diagnosis    of, 

130 

disinfection  during  attack,  130 
general  description  of  micro- 
organisms of,  130,  131 
poisons,  130 
Virulence,  42,  61,  211 
Virus,  211 

filterable,  199 
Vulvovaginitis,  89,  91 


W 

WATER,  bacteria  in,  180 
cholera  spirilla  in,  181 
colon  bacilli  in,  182 
diseases  transmitted  by,  62,  63, 

181 

dysentery  bacillus  in,  182 
examination  of,  182 
purification  of,  181 
typhoid  bacilli  in,  109, 181 

fever  from,  109 
Water-borne  diseases,  181 
Welch,  bacillus  aerogenes  capsula- 

tus  of,  167 
Whooping-cough,  133 

Bordet-Gengou     bacillus     in, 

133 

general  description  of,  133 
Widal  reaction,  68,  112 

collection  of  blood  for,  76 


YEASTS,  21,  171 
diseases  due  to,  172 
general  description  of,  171,  172 
pathogenic  powers  of,  172,  173 
relation  to  blastomycosis,  172 

Yellow  fever,  63,  202 

mosquitoes  in,  63,  202,  231 


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